Self-Injection Lock Bidirectional Optical Wireless System
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Solution Overview
Problem
Conventional free space optical wireless communication systems face issues with high energy consumption, high cost, and reduced signal-to-noise ratio due to optical power attenuation, especially in long-distance links like MRR, which limits their applicability and efficiency.
Innovation Solution
A wavelength tunable bidirectional optical wireless communication system utilizing self-injection lock technology at the optical node and passive retroreflectors with multiple lenses, combined with a tunable bandpass filter and optical modulators, to enhance transmission power, modulation bandwidth, and reduce spectral linewidth while minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If optical amplifier (EDFA/SOA) is added at the optical node to amplify optical signals, then transmission power is increased, but noise and energy consumption increase simultaneously
Solution Approach 1:
The patent replaces the conventional optical amplifier (EDFA/SOA) with a self-injection locked laser system. The slave laser at the optical node is injection-locked by the master laser signal from the optical terminal, enabling the slave laser to oscillate at the master laser's frequency with amplified power. This substitution eliminates the need for separate optical amplifiers, reducing noise and energy consumption while achieving the required transmission power through the injection locking mechanism itself.
2Power
If optical amplifier (EDFA/SOA) is added at the optical node to amplify optical signals, then transmission power is increased, but noise increases simultaneously
Solution Approach 1:
The patent replaces the conventional optical amplifier (EDFA/SOA) with a self-injection locked laser system. The slave laser at the optical node is injection-locked by the master laser signal from the optical terminal, enabling the slave laser to oscillate at the master laser's frequency with amplified power. This substitution eliminates the need for separate optical amplifiers, reducing noise and energy consumption while achieving the required transmission power through the injection locking mechanism itself.
3Ease of operation
If conventional symmetric architecture with light sources at both ends is used, then communication capability is achieved, but system complexity and cost increase
Solution Approach 1:
The patent transforms the conventional symmetric FSOWC architecture into an asymmetric architecture. The optical terminal is equipped with a master laser that transmits unmodulated light, while the optical node uses a slave laser that is injection-locked by the master laser. This asymmetric design eliminates the need for light sources at both ends, simplifying the system while maintaining bidirectional communication capability through the injection locking mechanism.
Solution Approach 2:
The master laser at the optical terminal serves multiple functions: it provides the injection signal for the slave laser at the optical node, enabling both uplink and downlink communication. The same master laser signal is used for wavelength locking and power amplification through the slave laser, reducing the need for separate components and simplifying the overall system architecture.
4Length of stationary object
If MRR Link is used for long-distance communication, then transmission distance is extended, but optical power attenuation increases proportionally to 1/R^4
Solution Approach 1:
The patent implements preliminary action by equipping the optical terminal with a master laser that transmits unmodulated light before the actual communication occurs. This master laser signal pre-establishes the optical path and enables the slave laser at the optical node to lock onto the correct frequency. The self-injection locking mechanism then amplifies the signal power, compensating for the 1/R^4 attenuation and enabling long-distance communication with adequate signal-to-noise ratio.
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
This solution achieves low energy consumption, high signal-to-noise ratio, and flexible wavelength capabilities, improving the efficiency and cost-effectiveness of optical wireless communication systems by increasing transmission power and modulation bandwidth while reducing spectral linewidth.
Implementation Method 1
combines and utilizes the self-injection locking (SIL) technology at the optical node and the optical terminal uses multiple lenses and passive retroreflectors to achieve the FSOWC with low energy consumption and high SNR
Implementation Method 2
a passive retroreflector for passively reflecting incident light parallel to path of original incident light
Implementation Method 3
an optical modulator arranged on one side of the passive retroreflector, wherein the optical modulator outputs a reversing light beam with signal
Implementation Method 4
a beamsplitter arranged on the path of the incident light beams to split the incident light beams which pass through the tunable bandpass filter into a first split beam and a second split beam
Implementation Method 5
a tunable bandpass filter arranged on the path of the incident light beams for the specific wavelength range in the incident light beams to pass through
Data Source
AI summary
A wavelength tunable bidirectional optical wireless communication system based on self-injection lock includes one optical node and multiple optical terminals, wherein the optical node consists of a tunable filter and a self-injection lock system to replace the conventional optical amplifier while achieving an amplified optical power, increasing the modulation bandwidth, wavelength adjustment and reducing the linewidth of each wavelength, in a low noise criteria. The optical terminal is composed by a modulated retroreflector to achieve the purpose of lightweight and low power consumption.