Contract analysis

1. Waveguide Structure Referring now to FIG. 2, the waveguide multiplexer of the present invention is fabricated on a silicon-on-insulator (SOI) platform. The SOI substrate comprises a silicon handle wafer 206, a buried oxide (Box) layer 204 disposed on the silicon handle wafer 206, and a silicon device layer disposed on the box layer 204. The silicon device layer is patterned to form the silicon core 202 of the opti

2. Multiplexer Architecture Referring now to FIG. 1 and FIG. 3, the waveguide multiplexer 100 of the present invention comprises a plurality of input waveguides 102a–102h, a coupling region 104, and a single output waveguide 106. In the 8-channel embodiment illustrated in FIG. 3, eight input waveguides 302a–302h are routed from input ports 302a–302h at the periphery of the photonic integrated circuit to the coupling

3. Low Insertion Loss Design Referring now to FIG. 4, the waveguide multiplexer of the present invention achieves low insertion loss through several specific design features that collectively reduce the dominant loss mechanisms in silicon photonic waveguide multiplexers. Adiabatic Tapers. Tapered waveguide transitions 402 are disposed at the interfaces between the input waveguides 102a–102h and the coupling region 10

4. Integration into Transceiver Modules Referring now to FIG. 7, the waveguide multiplexer of the present invention is designed for monolithic or hybrid integration into silicon photonic transceiver modules for data-center interconnect applications. In the embodiment illustrated in FIG. 7, the waveguide multiplexer 702 is integrated onto a silicon photonic integrated circuit (PIC) 710 along with a plurality of optica

5. Alternative Embodiments 4-Channel Configuration. In a first alternative embodiment, the waveguide multiplexer comprises four input waveguides and is configured to combine four wavelength channels onto a single output waveguide. The 4-channel configuration is suitable for 400G-DR4 transceiver modules and other lower-bandwidth applications where a reduced channel count is sufficient. The 4-channel configuration offe

6. Relationship to Thermal Management The performance of silicon photonic waveguide multiplexers is sensitive to temperature variations due to the thermo-optic coefficient of silicon (approximately 1.86 × 10⁻⁴ /°C at 1550 nm). Temperature changes shift the center wavelength of each channel in the multiplexer, which can degrade insertion loss and crosstalk performance if the channel wavelengths shift outside the passb

1. A multi-channel silicon photonic waveguide multiplexer, comprising: a silicon-on-insulator substrate comprising a silicon device layer disposed on a buried oxide layer; a plurality of input waveguides formed in the silicon device layer, each input waveguide configured to receive an optical signal at a respective wavelength; a coupling region configured to combine the plurality of optical signals of different wavel

2. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein the plurality of input waveguides comprises at least 8 input waveguides, each configured to receive an optical signal at a respective one of at least 8 different wavelengths.

3. The multi-channel silicon photonic waveguide multiplexer of claim 1, further comprising a mode-matching structure disposed in the coupling region and configured to minimize modal mismatch between the plurality of input waveguides and the single output waveguide, wherein the mode-matching structure comprises at least one of a tapered slab region, a multimode interference coupler section, or a stepped waveguide tran

4. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein a channel spacing between adjacent ones of the respective wavelengths is approximately 200 GHz or approximately 400 GHz, corresponding to a standard dense wavelength-division multiplexing (DWDM) wavelength grid.

5. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein each of the plurality of tapered waveguide transitions comprises an adiabatic taper having a taper length of at least 50 µm, the adiabatic taper configured such that substantially all optical power remains in a fundamental guided mode throughout the tapered waveguide transition.

6. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein the silicon device layer of the silicon-on-insulator substrate has a thickness of between 200 nm and 300 nm.

7. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein the waveguide multiplexer achieves an insertion loss of less than approximately 1.0 dB per channel across the wavelength range of at least 35 nm.

8. The multi-channel silicon photonic waveguide multiplexer of claim 1, further comprising a wavelength-tuning element operably coupled to at least one of the plurality of input waveguides or to the coupling region, the wavelength-tuning element configured to adjust a center wavelength of at least one channel of the waveguide multiplexer.

9. The multi-channel silicon photonic waveguide multiplexer of claim 1, further comprising means for coupling optical signals from the single output waveguide into a single-mode optical fiber.

10. A method of multiplexing a plurality of optical signals of different wavelengths, comprising: receiving, at each of a plurality of input waveguides formed in a silicon device layer of a silicon-on-insulator substrate, an optical signal at a respective wavelength; guiding each optical signal through a respective tapered waveguide transition disposed between a respective input waveguide and a coupling region, where

11. The multi-channel silicon photonic waveguide multiplexer of claim 1, wherein the waveguide multiplexer is integrated into an optical transceiver module for data-center interconnect applications, and wherein the single output waveguide is optically coupled to an output optical fiber.

12. The multi-channel silicon photonic waveguide multiplexer of claim 11, wherein the optical transceiver module is configured to operate as a 400G-ZR coherent transceiver module or an 800G-DR transceiver module in compliance with applicable industry-standard specifications.

13. The multi-channel silicon photonic waveguide multiplexer of claim 1, further comprising a cascaded arrangement of coupling stages, comprising: a first plurality of coupling stages, each configured to combine a respective subset of the plurality of optical signals onto a respective intermediate waveguide; and a second coupling stage configured to combine optical signals from the respective intermediate waveguides

14. A silicon photonic integrated circuit, comprising: the multi-channel silicon photonic waveguide multiplexer of claim 1; a plurality of optical modulators formed on the silicon-on-insulator substrate, each optical modulator coupled to a respective one of the plurality of input waveguides and configured to modulate an optical carrier signal at the respective wavelength with data; at least one laser source optically