Optical Amplifier Gain Spectrum Flattening via Phase Shifter
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Solution Overview
Problem
Optical parametric amplifiers (OPAs) have narrow amplification bands and non-flat gain spectra, making them impractical for use due to high cost configurations and low gain flatness, which is not suitable for optical communication systems.
Innovation Solution
Incorporating relative phase shifters into the optical gain fiber to shift the phase of the pump light without affecting the signal light, thereby flattening and broadening the gain spectrum, and using a configuration with an optical coupler and bandpass filter to enhance amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two pump lights are used to flatten the gain spectrum of an OPA, then the gain flatness is improved, but the device complexity and cost increase
Solution Approach 1:
The patent changes the phase parameter of the pump light by inserting a relative phase shifter into the optical gain fiber. This phase shifting modifies the nonlinear interaction characteristics, thereby flattening the gain spectrum without requiring multiple pump light sources, resolving the contradiction between gain flatness and device complexity
Solution Approach 2:
The relative phase shifter acts as an intermediary element inserted into the optical gain fiber. It mediates the phase relationship between pump light and signal light, enabling gain spectrum flattening through controlled phase modulation rather than through complex multi-pump configurations
2Manufacturing precision
If relative phase shifters are inserted into the optical gain fiber, then the gain spectrum flatness is improved, but the device complexity increases
Solution Approach 1:
The relative phase shifter modifies the phase parameter of the pump light within the existing optical gain fiber structure. This single parameter change (phase) achieves gain spectrum flattening without adding multiple pump sources or complex optical paths, minimizing the increase in device complexity
3Manufacturing precision
If phase of pump light is shifted, then the gain spectrum is flattened, but the amplification band may be affected
Solution Approach 1:
The patent carefully controls the phase shifting parameter to flatten the gain spectrum while maintaining the amplification band characteristics. By adjusting the relative phase shift amount, the system achieves gain flatness without significantly narrowing the useful amplification bandwidth, balancing both requirements
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 approach results in a more practical OPA with increased gain spectrum flatness, reduced noise figure, and improved amplification efficiency, making it suitable for optical communication systems.
Implementation Method 1
an optical parametric amplifier (OPA), as disclosed in JP 2008 089781 A, which makes use of nonlinear effect in an optical fiber for optical amplification
Implementation Method 2
at least one relative phase shifter is inserted into the optical gain fiber... shift the phase of the pump light without changing the phase of the signal light
Data Source
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AI summary
An optical amplifier includes an optical gain fiber into which signal light and pump light are input and at least one relative phase shifter is inserted. Preferably, the relative phase shifter is inserted so that the relative phase in the lengthwise direction of the optical gain fiber falls within a predetermined range containing 0.5 n. Preferably, the optical gain fiber is a highly non-linear optical fiber having a non-linearity constant of at least 10/W/km. Preferably, the dispersion of the optical gain fiber is within the range from -1 ps/nm/km to 1 ps/nm/km in an amplification band. Preferably, the absolute value of the dispersion slope of the optical gain fiber at a zero dispersion wavelength is no greater than 0.05 ps/nm2/km.