Fiber Light Source Wavelength Stability via Depolarized Pumping
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Solution Overview
Problem
Fiber light sources (FLS) in interferometric fiber optic gyroscopes face reliability and mean wavelength stability issues due to pump laser instability, particularly from polarization hole burning effects in Erbium Doped Fiber, which are exacerbated by the need for backup pump schemes that compromise wavelength stability.
Innovation Solution
A broadband light source configuration using a 2×2 polarization maintaining coupler, polarization beam combiner, and wavelength division multiplexer to convert polarized pump beams into unpolarized beams, reducing sensitivity to pump polarization fluctuations and allowing for efficient backup schemes without power wastage, featuring a doped optical fiber that generates stable broadband amplified spontaneous emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 2×2 fiber coupler is used to combine outputs of two pump lasers for backup reliability, then FLS reliability is improved, but half of the pump power is wasted in single-end pumping scheme
Solution Approach 1:
The system divides the pump power distribution into two independent single-end pumping paths, each capable of operating alone. This segmentation allows each pump laser to operate at full power to its respective EDF without the 50% power loss inherent in combined pumping schemes, while maintaining backup capability through the segmented architecture.
2Use of energy by moving object
If dual-end pumping schemes are used to improve pump efficiency, then power utilization is improved, but wavelength stability is compromised due to sensitivity to power splitting ratio changes
Solution Approach 1:
The invention extracts and eliminates the problematic 2×2 fiber coupler from the pumping system. By removing this power-splitting component, the system avoids the wavelength instability caused by power splitting ratio changes, while still achieving efficient pump utilization through the alternative single-end pumping architecture with backup capability.
3Stability of the object's composition
If pump laser polarization states are tightly controlled to reduce polarization hole burning effects, then wavelength stability is improved, but device complexity increases
Solution Approach 1:
The invention converts the harmful polarization hole burning effect into a beneficial situation by using depolarized pump light. Instead of trying to control and maintain specific polarization states (which adds complexity), the system deliberately depolarizes the pump light to excite both polarization modes equally in the EDF, thereby eliminating the polarization hole burning effect and its associated wavelength instability without requiring complex polarization control mechanisms.
4Stability of the object's composition
If polarization multiplexing of two pump lasers with equal power and orthogonal polarization states is used, then wavelength stability is improved, but strict requirements on polarization state and power control are imposed
Solution Approach 1:
Instead of using polarized pump light that requires strict polarization state control and multiplexing arrangements, the invention inverts the approach by using depolarized pump light. This inversion simplifies the operation by eliminating the need for precise polarization alignment and power balancing between multiple pumps, while still achieving wavelength stability through the depolarized pumping scheme that avoids polarization hole burning.
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 stable broadband amplified spontaneous emission with minimal wavelength variation, enhancing the reliability and stability of fiber light sources by reducing polarization-induced instabilities and enabling efficient dual-pump operation without power loss.
Implementation Method 1
an optical system including a polarization beam combiner, configured to receive at least one optical pump beam having a respective at least one pump coherence length from a respective one of the at least one optical pump source
Implementation Method 2
a solid state laser medium. The optical system is configured to receive at least one optical pump beam having a respective at least one pump coherence length from a respective one of the at least one optical pump source. The solid state laser medium receives a substantially unpolarized pump beam from a first output of the optical system. Stable broadband amplified spontaneous emission is output from a second output of the optical system
Data Source
AI summary
A broadband light source configured to emit a stable broadband optical beam is provided. The broadband light source includes at least one optical pump source, an optical system including a polarization beam combiner, and a solid state laser medium. The optical system is configured to receive at least one optical pump beam from a respective one of the at least one optical pump source. The solid state laser medium receives a substantially unpolarized pump beam from a first output of the optical system. Stable broadband amplified spontaneous emission is output from a second output of the optical system.