Obviousness

To analyze the obviousness of US patent 9448367 under 35 U.S.C. § 103, we will consider combinations of prior art references that would make the claims, particularly independent Claim 1, obvious to a person having ordinary skill in the art (PHOSITA). The primary problem addressed by US9448367 is the challenge of accommodating multi-channel Transmitter Optical Subassemblies (TOSA) and Receiver Optical Subassemblies (ROSA) within the limited space of Optical Line Terminal (OLT) transceiver modules, where conventional LC adapters may not fit. The patent proposes a "dual fiber type direct link adapter" that uses optical fibers directly coupled to the TOSA and ROSA, thereby reducing the adapter's size and enabling a smaller transceiver module.

Independent Claim 1 of US9448367 describes:
"A dual fiber type direct link LC adapter comprising:
an adapter body portion defining first and second LC connector receiving regions at a pluggable connector end and defining first and second slots at a direct link end;
first and second direct link connector assemblies configured to be received in the first and second slots, respectively, each of the direct link connector assemblies defining an LC connector receptacle at one end, wherein the LC connector receptacle extends into a respective one of the LC connector receiving regions and is configured to receive a portion of an LC connector for optical coupling, and wherein each of the direct link connector assemblies is configured to be mechanically coupled to an optical fiber at another end; and
an adapter cover portion configured to cover the first and second slots for retaining the direct link connector assemblies in the respective slots."

The term "direct link" is defined in US9448367 as "optically coupling with a single optical fiber mechanically coupled between two components without using pluggable connectors at the ends of the fiber link" (US9448367, Detailed Description).

We will combine prior art references to demonstrate how the elements of Claim 1 would have been obvious.

Obviousness Combination

A PHOSITA, seeking to overcome the space constraints in OLT transceiver modules as articulated in the background of US9448367 (US9448367, Background Information), would be motivated to combine the teachings of existing optical transceiver designs and internal fiber coupling mechanisms.

Combination: US7090509B1 (Stratos) + US20110103797A1 (Sumitomo)

1. Primary Reference: US7090509B1 to Stratos International, Inc. ("Multi-port pluggable transceiver (MPPT) with multiple LC duplex optical receptacles")

US7090509B1 describes a "multi-port pluggable transceiver (MPPT) with multiple LC duplex optical receptacles". This reference establishes the concept of a transceiver module having an adapter body portion that defines multiple LC connector receiving regions at a pluggable connector end. Such receptacles are designed to receive external LC connectors for optical communication.

2. Supporting Reference: US20110103797A1 to Sumitomo Electric Industries, Ltd. ("Pluggable optical transceiver and method for manufacturing the same")

US20110103797A1 describes a pluggable optical transceiver that includes an internal optical connection structure. Specifically, it teaches a "ferrule on which a tip end of the optical waveguide is fixed, and a sleeve which is adapted to accept another ferrule of another optical connector to be optically connected to the ferrule via the sleeve are disposed in the connector receptacle". This directly teaches a "direct link connector assembly" in which an optical fiber is mechanically coupled to a ferrule at one end, and that ferrule (within a sleeve) forms a receptacle for an external LC connector.

Motivation for Combination and Remaining Elements:

The background of US9448367 explicitly states the challenge of integrating multi-channel TOSAs and ROSAs into small form factor OLT transceiver modules because conventional LC adapters consume too much space (US9448367, Background Information). A PHOSITA, faced with this known problem of miniaturization, would be motivated to combine the multi-port LC receptacle capability of a transceiver (as shown in US7090509B1) with the compact, internal fixed-fiber ferrule arrangement (as shown in US20110103797A1). The goal would be to create a more compact optical interface.

By combining these references:

• "an adapter body portion defining first and second LC connector receiving regions at a pluggable connector end": US7090509B1 clearly provides a multi-port transceiver with multiple LC duplex optical receptacles, which inherently defines such receiving regions.
• "defining first and second slots at a direct link end": When designing a compact module to house internal, fixed-fiber connector assemblies (as per US20110103797A1's teaching of an optical fiber mechanically fixed to a ferrule), a PHOSITA would find it obvious to design the adapter body with "slots" for receiving and aligning these components. This is a common mechanical design practice for modular assembly and space optimization.
• "first and second direct link connector assemblies configured to be received in the first and second slots, respectively, each of the direct link connector assemblies defining an LC connector receptacle at one end, wherein the LC connector receptacle extends into a respective one of the LC connector receiving regions and is configured to receive a portion of an LC connector for optical coupling, and wherein each of the direct link connector assemblies is configured to be mechanically coupled to an optical fiber at another end": US20110103797A1 precisely describes such an assembly where an optical fiber is mechanically fixed to a ferrule, and that ferrule/sleeve combination forms a receptacle for an external LC connector. It would be obvious to a PHOSITA to replicate this structure for a dual-fiber (first and second) configuration to support the duplex nature of the LC interface provided by US7090509B1.
• "an adapter cover portion configured to cover the first and second slots for retaining the direct link connector assemblies in the respective slots": Securing internal components within a housing is a routine engineering task. The use of an adapter cover to retain assemblies within slots is a common and predictable mechanical solution for ensuring robust optical and mechanical integrity in a compact device.

Conclusion:

The combination of US7090509B1 and US20110103797A1, driven by the well-known need to miniaturize optical transceiver modules for high-density applications as highlighted in the background of US9448367, would render the subject matter of Claim 1 of US9448367 obvious to a person having ordinary skill in the art. The specific mechanical arrangements for slots, retention, and dimensions claimed in the dependent claims are routine engineering optimizations that would naturally flow from this combination in pursuit of a compact design.