Optical Waveguide Soliton Spectral Narrowing
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Solution Overview
Problem
Conventional wavelength tunable light sources emit optical pulses with a spectral width that is too broad for high-accuracy measurements in optical tomography and other applications, requiring a method to narrow the spectral width while minimizing noise.
Innovation Solution
An optical waveguide member with specific dispersion characteristics is used to cause a soliton effect in the input optical pulse, narrowing its spectral width by increasing the absolute value of the second-order dispersion value (β2) in the propagation direction, thereby reducing the spectral width and suppressing noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an ultrashort optical pulse is used to achieve high-speed wavelength tuning, then the wavelength can be changed rapidly without mechanical adjustment, but the spectral width becomes too broad (about 20 nm) for high-accuracy measurements
Solution Approach 1:
The patent changes the dispersion parameter (second-order dispersion value β2) along the propagation direction in the optical waveguide member. By making the absolute value of β2 increase in the propagation direction, the soliton effect is enhanced, which narrows the spectral width of the optical pulse while maintaining the wavelength tuning capability, thus resolving the contradiction between fast tuning and measurement accuracy
2Measurement precision
If the spectral width of the optical pulse is narrowed to improve measurement accuracy, then measurement precision improves, but noise components (pedestal) may increase
Solution Approach 1:
The patent applies local quality by creating a spatially varying dispersion profile within the optical waveguide member. The second-order dispersion value β2 is specifically designed to increase in absolute value along the propagation direction, which locally enhances the soliton effect in different sections of the waveguide. This localized control of dispersion properties achieves spectral narrowing while suppressing noise through the progressive soliton formation process
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 method achieves a high narrowing factor for the spectral width of the optical pulse, resulting in a clear output pulse with a low noise component, suitable for high-resolution applications such as optical tomography and spectroscopy.
Implementation Method 1
The wavelength tunable light source of Patent Document 1 uses the soliton effect that is the interaction between self-phase modulation and wavelength dispersion
Implementation Method 2
uses the soliton effect that is the interaction between self-phase modulation and wavelength dispersion
Implementation Method 3
uses the soliton effect that is the interaction between self-phase modulation and wavelength dispersion
Implementation Method 4
As the optical pulse propagates in the optical fiber, the pulse wavelength shifts to the long wavelength side due to the soliton self-frequency shift effect of the optical fiber
Data Source
AI summary
The present invention provides a method for narrowing a spectral width that can also be adapted to an ultrashort optical pulse emitted from a wavelength tunable light source, and that can provide an output optical pulse with a narrow spectral width and a low noise component, and an optical element and a light source device that use the method for narrowing a spectral width. The method includes using an optical waveguide member (2) to cause a soliton effect in an input optical pulse (1) within the optical waveguide member (2), thereby narrowing a spectral width of the input optical pulse (1) to provide an output optical pulse (3), the optical waveguide member (2) having dispersion characteristics such that the average of a second-order dispersion value (β2) with respect to the input optical pulse (1) is negative, and the absolute value of the second-order dispersion value (β2) increases in a propagation direction of the input optical pulse (1).