FMCW Range Scanning With Switchable SOAs for Lower Power
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Solution Overview
Problem
Existing FMCW LiDAR systems face challenges with high power consumption and thermal issues due to internal losses in optical switches, which are not adequately addressed by previous solutions involving smaller loss optical switches or the use of SOAs with pre-amplifiers leading to detector saturation.
Innovation Solution
A device utilizing switchable semiconductor optical amplifiers (SOAs) for fast switching between optical channels, combined with a control scheme that alternates the SOA states in processing units to emit light from one free-space coupler at a time, allowing for high measuring rates and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical switches are used in switching matrix to distribute optical signals, then optical signal routing is achieved, but internal losses significantly reduce light intensity
Solution Approach 1:
The patent extracts the amplification function from the switching matrix and places it at the output stage through semiconductor optical amplifiers (SOAs). This separates the routing function (switching matrix) from the intensity compensation function (SOAs), allowing each to be optimized independently. The SOAs are positioned after the switching matrix to amplify the already-routed signals without interfering with the switching operation.
Solution Approach 2:
The patent introduces semiconductor optical amplifiers as intermediary components between the switching matrix and the free-space couplers. These SOAs act as mediators that compensate for the losses introduced by the optical switches, restoring light intensity to acceptable levels without modifying the switching matrix architecture itself.
2Loss of energy
If light amplifiers are used to compensate for losses in optical switches, then light intensity is restored, but power consumption increases
Solution Approach 1:
The patent applies amplification locally only at the output channels where light intensity needs compensation, rather than amplifying all signals throughout the system. The SOAs are positioned specifically at the output of the switching matrix where losses have already occurred, providing targeted amplification only where needed, thus minimizing overall power consumption.
3Loss of energy
If light amplifiers are used to compensate for losses in optical switches, then light intensity is restored, but thermal problems occur
Solution Approach 1:
The patent extracts the thermal management challenge from the switching matrix and relocates it to dedicated SOA modules at the output stage. This separation allows for independent thermal management of the amplification function, potentially using heat sinks or other cooling mechanisms specifically at the SOA locations without affecting the overall system thermal balance.
4Loss of energy
If pre-amplifiers are used to amplify laser signal before 3 dB couplers, then sufficient input power for SOAs is provided, but detector saturation occurs due to amplified local oscillator signal
Solution Approach 1:
The patent performs preliminary amplification of the laser signal before the 3 dB couplers using pre-amplifiers, but does so in a controlled manner. The amplification is applied to the local oscillator signal before it reaches the SOAs, ensuring that the SOAs receive sufficient input power for effective operation. The key is that this preliminary amplification is balanced with the subsequent SOA amplification to prevent detector saturation.
Solution Approach 2:
The patent adjusts the amplification parameters of both the pre-amplifiers and the SOAs to achieve the desired balance. By carefully controlling the gain of these amplification stages, the system provides sufficient input power to the SOAs while keeping the amplified local oscillator signal at levels that do not cause detector saturation. This involves optimizing the amplification parameters based on the specific system requirements.
Data Source
AI summary
A device for scanning measurement of the range to an object has a frequency-modulated continuous wave light source, a light splitter splitting the light into a plurality of light portions, and a plurality of processing units. Each unit has a switchable semiconductor optical amplifier, N free-space couplers, emitting the light portion, and a 1×N switching matrix including a plurality of optical switches. A control unit controls the switchable semiconductor optical amplifier and the switching matrix of each processing unit such that, at a given time, only the switchable semiconductor optical amplifier of one processing unit is in an “on” state and only one of the free-space couplers of said one processing unit emits the light portion. If a switchable semiconductor optical amplifier of a processing unit is in an “off” state, at least one of the optical switches in the switching matrix of another processing unit is operated.