Photonic Integrated Transceiver With SOA-Based Laser Power Splitting
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Solution Overview
Problem
Optical transceivers with shared lasers face challenges in optimizing both transmit and local oscillator power, leading to suboptimal performance due to differing optimal power levels for signal-to-noise ratio and sensitivity.
Innovation Solution
A photonic integrated circuit with semiconductor optical amplifiers (SOAs) in both the transmitter and receiver portions, allowing for independent power adjustment and optimization of the local oscillator signal, enabling improved signal-to-noise ratio and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a common laser is shared between transmitter and receiver portions, then electrical power is reduced and wavelength matching is improved, but optimal power levels for transmit and local oscillator signals cannot be independently optimized
Solution Approach 1:
The patent divides the common laser output into separate optical paths for transmitter and receiver portions. By segmenting the optical signal distribution, independent semiconductor optical amplifiers can be placed in each path to independently optimize power levels for transmit signals and local oscillator signals, resolving the contradiction between power efficiency and signal quality
Solution Approach 2:
Semiconductor optical amplifiers are introduced as intermediary devices in the optical paths. These amplifiers act as mediators that can independently boost the transmit optical signal and local oscillator signal to their respective optimal power levels, enabling independent optimization without requiring separate lasers while maintaining the power-saving benefit of laser sharing
2Reliability
If transmit optical power is optimized for signal-to-noise ratio, then transmit performance is improved, but local oscillator power may not be optimized for receiver sensitivity
Solution Approach 1:
The optical path is segmented into independent transmitter and receiver portions, each with its own semiconductor optical amplifier. This segmentation allows the transmit optical signal to be optimized for signal-to-noise ratio while the local oscillator signal is independently optimized for receiver sensitivity, eliminating the trade-off between these two performance metrics
Solution Approach 2:
Different quality requirements are applied to different parts of the optical system. The transmitter portion is optimized for high signal-to-noise ratio with appropriate power levels, while the receiver portion is optimized for maximum sensitivity with independently controlled local oscillator power. Each portion has tailored optimization rather than a compromise solution
3Area of stationary object
If transceiver components are integrated on a common substrate, then device size is reduced, but independent power control of optical paths becomes more complex
Solution Approach 1:
Multiple transceiver components including lasers, modulators, optical hybrids, photodiodes, and semiconductor optical amplifiers are merged and integrated on a common photonic integrated circuit substrate. This consolidation reduces the overall device size while the modular integration architecture enables independent power control through separate control interfaces for each functional block
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 use of SOAs in the transceiver's local oscillator path enhances sensitivity and power control, optimizing performance beyond traditional power limits and reducing noise, thereby improving the overall signal quality and efficiency.
Implementation Method 1
A first semiconductor optical amplifier is provided in the transmitter portion, such that an output of the transmitter portion is greater than an output of the transmitter portion in an absence of the first semiconductor optical amplifier
Implementation Method 2
A second semiconductor optical amplifier or variable optical attenuator is provided in the receiver portion to adjust a power of an optical input to the photodiode circuit
Implementation Method 3
the receiver portion may include optical hybrids that mix local oscillator light with an incoming optical signal, and photodiodes to detect the outputs of the optical hybrids
Data Source
AI summary
Consistent with the present disclosure, a transceiver is implemented as a photonic integrated circuit (PIC) that includes a transmitter and a receiver. A laser is also provided that provides light to a splitter, which supplies a first portion of the light to the transmitter and a second power of the light to the receiver. Semiconductor optical amplifiers (SOAs) are provided at one or more locations on the PIC. In one example, at least one SOA is provided in the transmitter so that the transmitted optical signal has a desired power, and at least another SOA is provided in the receiver so that the local oscillator signal has a desired power. In a further example, an SOA is provided in the receiver to boost the power of the received optical signal. Preferably, the transceiver, including the SOAs, is monolithically integrated on a substrate, such as a substrate including indium phosphide (InP). Moreover, the SOA can be readily controlled via a low voltage current source consuming minimal electrical power.