Stabilized Pump Laser Using Single-Mode Fiber and Bragg Grating
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Solution Overview
Problem
Existing laser pump sources face challenges in maintaining consistent wavelength stability over a wide temperature range (-60 to 90°C) due to unwanted propagation modes in polarization-maintaining optical fibers, leading to transmission inefficiencies and instability in pump output signals.
Innovation Solution
A laser pump system utilizing a light stabilizer with a single mode optical fiber configured to pass one axis of propagation to a Bragg grating, combined with a temperature stabilizer like a thermoelectric cooler, to generate a stabilized pump output signal, minimizing unwanted propagation modes and ensuring temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If polarization-maintaining optical fiber is used to generate coherent light output, then wavelength stability can be maintained, but unwanted propagation modes are launched causing transmission inefficiencies and output instability
Solution Approach 1:
The patent extracts only the desired single propagation mode from the optical fiber by using a single-mode fiber configuration that filters out unwanted propagation modes. The fiber is designed to support only one mode of light propagation, thereby eliminating the harmful multiple modes that cause instability while maintaining wavelength stability through the Bragg grating feedback mechanism.
2Adaptability or versatility
If temperature range is expanded from -60 to 90 deg C for operational flexibility, then adaptability is improved, but wavelength consistency becomes difficult to maintain
Solution Approach 1:
The patent implements a feedback mechanism using a Bragg grating that reflects a specific wavelength back to the laser diode, creating a feedback loop that stabilizes the output wavelength. This feedback control allows the system to maintain consistent wavelength across the wide temperature range of -60 to 90°C by continuously adjusting and correcting for temperature-induced wavelength shifts.
3Quantity of substance
If multiple propagation modes are launched in the fiber, then more light can be transmitted, but transmission efficiency decreases due to mode interference
Solution Approach 1:
The patent extracts and eliminates unwanted propagation modes by using a single-mode fiber configuration that permits only one mode of light propagation. This extraction of harmful multiple modes prevents mode interference and maintains high transmission efficiency, while the Bragg grating ensures sufficient light is transmitted back to the laser diode to maintain population inversion in the gain medium.
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 achieves improved wavelength and temperature stability, enhancing the efficiency and consistency of the pump output signal, particularly in fiber optic gyroscope applications, by rejecting undesired propagation modes and suppressing phase shifts and power degradations.
Implementation Method 1
a fiber Bragg grating is formed in the fiber which reflects a portion of the light from the laser diode back to the laser diode
Implementation Method 2
A thermoelectric cooler may be placed between the platform and a housing base
Data Source
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AI summary
A stabilized pump laser source (300, 500) includes a semiconductor laser source (310, 520) that generates a coherent output signal and a light stabilizer. The light stabilizer comprises an optical fiber configured to pass at least one polarization component to a Bragg grating to provide decoherent external reflections and to generate a stabilized pump output signal. The fiber may be a single mode fiber (320) mounted with the laser source (310) on a common temperature stabilized substrate (330). Alternatively, the fiber may be a polarizing fiber (540, 560) with sufficient extinction ratio to reject light of an incorrect polarization.