Coolerless Fiber Light Source for Harsh Environments
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Solution Overview
Problem
Conventional pump lasers in fiber optic gyrosopes and sensors are sensitive to temperature and radiation, leading to instability in mean wavelength and power, which is exacerbated by the absence of thermoelectric coolers, particularly in harsh environments like space applications.
Innovation Solution
A coolerless pump laser-based light source device incorporating a wavelength division multiplexer, optical isolator, amplified spontaneous emission unit, and temperature-compensated bandpass reflector, such as a fiber Bragg grating, to stabilize the mean wavelength and power of the light beam across a broad temperature range and under radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermoelectric cooler (TEC) is used to stabilize pump laser temperature, then the mean wavelength and peak power stability is improved, but the power consumption increases
Solution Approach 1:
The patent removes the thermoelectric cooler (TEC) from the pump laser assembly, extracting the temperature stabilization function from the active cooling system. This eliminates the power consumption associated with TEC operation while relying on passive thermal management and environmental conditions to maintain acceptable laser performance for space applications.
Solution Approach 2:
The pump laser is designed to operate without active cooling, allowing it to self-regulate temperature within acceptable ranges through passive heat dissipation and thermal equilibrium with the space environment. This self-service approach eliminates the need for external power-consuming cooling systems while maintaining functional reliability.
2Use of energy by moving object
If a coolerless pump laser is used to reduce power consumption, then the power consumption is reduced, but the mean wavelength and power stability under temperature variation deteriorates
Solution Approach 1:
The patent selects specific laser diode parameters and characteristics that are inherently more tolerant to temperature variations. By carefully choosing laser diodes with appropriate temperature coefficients and operating points, the system achieves acceptable wavelength stability without active cooling, transforming the temperature sensitivity parameter into a manageable characteristic.
Solution Approach 2:
The patent applies localized thermal management strategies, such as thermal isolation of the laser diode from extreme temperature fluctuations and targeted heat dissipation paths. This local quality approach ensures that the pump laser operates within a stable thermal micro-environment despite broader temperature variations in the space application context.
3Device complexity
If a coolerless pump laser is used for space applications, then the device complexity is reduced, but the sensitivity to radiation and temperature increases
Solution Approach 1:
The patent removes the thermoelectric cooler and associated control circuits, extracting the active temperature management subsystem. This reduction in device complexity eliminates multiple failure points and reduces the overall system mass and power requirements, accepting that the pump laser will operate without active temperature stabilization in the harsh space environment.
Solution Approach 2:
The patent employs commercially available, off-the-shelf laser diodes and optical components that are not specifically hardened for radiation environments. This approach uses standard, easily replaceable components rather than specialized radiation-resistant parts, reducing system complexity and cost while accepting that components may have limited operational lifetimes in harsh space conditions.
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 stable mean wavelength and power output over a wide temperature range and under radiation, making it suitable for space applications like fiber optic gyroscopes without the need for power-consuming thermoelectric coolers.
Implementation Method 1
A pump laser without a thermoelectric cooler is for providing a first light beam having a mean wavelength in a first band
Implementation Method 2
The first terminal of the wavelength division multiplexer receives the first light beam for allowing the first light beam having a mean wavelength in the first band to pass from the first terminal of the wavelength division multiplexer to a common terminal
Implementation Method 3
The optical isolator is a uni-directional guiding unit, whose first terminal is connected to the second terminal of the wavelength division multiplexer through at least one section of optic fiber. The first terminal of the optical isolator receives the second light beam from the second terminal of the wavelength division multiplexer, and allows the second light beam to pass from the first terminal of the optical isolator to a second terminal of the optical isolator
Implementation Method 4
A first terminal of the amplified spontaneous emission unit (such as rare-earth doped fibers) connects to the common terminal of the wavelength division multiplexer through at least one section of optic fiber. The first light beam having a mean wavelength in the first band excites amplification after being received by the first terminal of the amplified spontaneous emission unit, producing a third light beam to a second terminal of the amplified spontaneous emission unit
Implementation Method 5
The first terminal of the bandpass reflector receives the third light beam from the second terminal of the amplified spontaneous emission unit, reflecting the third light beam having a mean wavelength in a specific band back to the first terminal of the bandpass reflector and allowing the third light beam having a mean wavelength outside the specific band to pass from the first terminal of the bandpass reflector to the second terminal of the bandpass reflector
Data Source
AI summary
A robust broadband ASE (amplified spontaneous emission) fiber light source device outputs a light beam which is little affected by temperature and radiation. The light source device is a single-pass backward or double-pass backward architecture, and has a coolerless pump laser and temperature compensated bandpass reflector. The light source device may have a high pass filtering element disposed between the wavelength division multiplexer thereof and the optical isolator thereof, so as to compensate the effect of the temperature to the mean wavelength of the light beam. The specific band of the temperature compensated bandpass reflector which reflects the light beam, and the band which the high pass filtering element transmits the light beam are within the band which the ASE unit amplifies the light beam, and the high pass filtering element mainly absorbs the light beam outside the specific band.