Modulated Light Source Apparatus with Nonlinear Waveguide
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Solution Overview
Problem
Current light source apparatuses using nonlinear optical materials for wavelength conversion lack effective modulation capabilities, leading to instability and reduced practical light intensity, particularly in difference-frequency and sum-frequency generation, which limits their application in sensitive refractive index measurements and fluorescence microscopy.
Innovation Solution
A light source apparatus with a nonlinear optical material waveguide having a periodically modulated structure, utilizing two semiconductor lasers with different wavelengths, where one laser is stabilized by a narrowband FBG and the other has a diffraction grating, allowing for controlled current modulation to maintain practical light intensity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current light source apparatuses using nonlinear optical materials are used for wavelength conversion, then wavelength conversion can be achieved, but modulation capabilities are lacking leading to instability and reduced practical light intensity
Solution Approach 1:
The patent applies dynamics by enabling current control of the semiconductor laser light source to modulate the output light intensity. The control unit dynamically adjusts the drive current based on modulation signals, allowing the wavelength conversion device to achieve both stability through controlled operation and adaptability through variable intensity output. This resolves the contradiction by making the system dynamically adjustable rather than static.
Solution Approach 2:
The patent changes the operational parameters by controlling the drive current of the semiconductor laser within specific ranges. By adjusting the current parameter, the system achieves stable wavelength conversion while enabling modulation capabilities. The control unit modifies the current parameter in response to modulation signals, allowing the system to maintain reliability while gaining adaptability for different application requirements.
2Illumination intensity
If high intensity pumping light is used to increase light output, then more wavelength converted light is generated, but mode jumps occur and stability is reduced
Solution Approach 1:
The patent implements feedback control where the control unit monitors the operating conditions and adjusts the drive current to prevent mode jumps. By using feedback mechanisms, the system can maintain stable operation even at higher light output levels. The control unit receives information about the laser's operational state and makes real-time adjustments to keep the system within stable operating parameters while maximizing light output.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively controlling the drive current to prevent mode jumps before they occur. The control unit is designed to anticipate and prevent instability by maintaining current within optimal ranges, thereby counteracting potential mode jumps before they can disrupt stability. This allows the system to operate at high intensities without suffering from the harmful effects of mode jumps.
3Device complexity
If wavelength conversion is performed without modulation control, then the apparatus is simpler, but practical light intensity is reduced and sensitivity is limited
Solution Approach 1:
The patent achieves multi-functionality by integrating modulation capabilities into the existing wavelength conversion apparatus without requiring completely separate systems. The control unit serves multiple functions: it maintains stable operation, enables modulation for sensitivity enhancement, and adapts to different application requirements. This universal control mechanism adds measurement precision and sensitivity while maintaining relative apparatus simplicity through a unified control architecture.
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 enables stable and high-intensity modulation of wavelength-converted light, enhancing the sensitivity of refractive index measurements and fluorescence microscopy by maintaining light output within the pseudo-phase matching band, reducing noise, and preventing mode jumps.
Implementation Method 1
a visible, middle infrared or infrared light source using second-harmonic generation, difference-frequency generation or sum-frequency generation effect produced in a nonlinear optical medium
Implementation Method 2
the waveguide 12 converts the pumping light A to difference frequency light C with a wavelength λ3
Implementation Method 3
the wavelength converted light C with a wavelength λ3=0.59 μm, which is yellow visible light, is obtained by the sum-frequency generation
Implementation Method 4
The FBG, which has a Bragg diffraction grating formed in a core section of an optical fiber, is an optical fiber type device with a characteristic of reflecting only light with a particular wavelength
Implementation Method 5
The DFB laser is a semiconductor laser that oscillates laser light by confining light to an active region by operating a periodic shape built in a laser chip as a diffraction grating, and by reflecting only light with a particular wavelength
Data Source
AI summary
A light source apparatus with modulation function has a wavelength conversion module (75) composed of a nonlinear optical material with a structure having a nonlinear constant modulated periodically. It outputs a difference frequency or sum frequency produced by multiplexing pumping light from semiconductor laser light sources (71) and (72) with different wavelengths through a WDM coupler (74) and by launching the multiplexed light into the optical waveguide. The semiconductor laser light source (72) includes a diffraction grating. The semiconductor laser light source (71) includes a section for modulating output light emitted from its semiconductor laser, and is connected to an external FBG (73) which has a reflection band narrower than a resonance wavelength spacing determined by the device length of the semiconductor laser. The FBG (73) is supplied with the modulated output.