Silicon Photonics Transceiver Reference Loop Alignment
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Solution Overview
Problem
There is a need for a single-wavelength 100 Gbit/s PAM4 pluggable transceiver based on silicon photonics technology for C-band DWDM applications, as existing solutions do not utilize silicon photonics for such applications.
Innovation Solution
A transceiver design incorporating a silicon photonics modulator chip with a Mach-Zehnder interferometer and a reference loop, enabling passive or active alignment of the fiber array coupler, which reduces the number of optical components and allows for easier alignment, and uses a single DWDM laser source to transmit a single wavelength PAM4 signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon photonics modulator chip is used, then cost and footprint are reduced, but alignment precision between fiber array coupler and chip becomes more critical
Solution Approach 1:
A reference loop is introduced as an intermediary alignment reference between the fiber array coupler and the silicon photonics modulator chip. The reference loop provides a visible optical path that enables precise alignment of the fiber array coupler to the chip input interface without requiring the chip to be operational, thereby resolving the alignment precision challenge while maintaining cost benefits of silicon photonics
Solution Approach 2:
The reference loop is configured to enable alignment to be performed before the silicon photonics modulator chip is operational or powered on. This preliminary alignment action ensures precise positioning of the fiber array coupler relative to the chip input interface in advance, eliminating alignment difficulties that would arise if the chip needed to be active during the alignment process
2Ease of operation
If reference loop is added for alignment, then alignment ease is improved, but device complexity increases
Solution Approach 1:
The reference loop is merged with the main optical path by coupling it at a tap point in the optical circuit. This combining approach allows the reference loop to serve dual purposes: providing alignment reference functionality while simultaneously being part of the operational optical path, thereby minimizing additional complexity and component count
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective, low-latency, and high-performance transceiver with reduced optical component requirements, enabling efficient data transmission over C-band DWDM links, leveraging the benefits of silicon photonics such as CMOS compatibility, low cost, and small footprint.
Implementation Method 1
A Mach-Zehnder interferometer disposed between the laser input interface and the signal output interface
Implementation Method 2
a first photodetector disposed between the laser input interface and the Mach-Zehnder interferometer; a second photodetector disposed between the signal output interface and the Mach-Zehnder interferometer
Data Source
AI summary
A silicon photonics based single wavelength 100 Gbit/s PAM4 DWDM transceiver in a pluggable form factor having a transmitter, said transmitter having: a DWDM laser source; a fiber array pigtail having a polarization maintaining fiber and an output single mode fiber; a silicon photonics modulator chip configured to optically connect to the DWDM laser source through the usage of the polarization maintaining fiber, a modulator driver chip connected to the silicon photonics modulator chip and an LC receptacle configured to optically connect to the silicon photonics modulator chip through the usage of the output single mode fiber. The disclosed transmitter may be further comprised of a reference loop within the silicon photonics modulator chip to allow for the utilization of a passive alignment approach for optically connected elements. The disclosed transceiver may be configured for use with C-band DWDM applications for utilization in applicable technologies, including 5G telecommunications.