Wavelength-Tunable Laser with Dithering Feedback Control
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Solution Overview
Problem
Existing wavelength-tunable lasers face challenges in achieving stable single-mode emission and accurate wavelength control due to narrow channel spacing in semiconductor lasers and difficulties in amplifying laser light output from semiconductor optical amplifiers.
Innovation Solution
A wavelength-tunable laser device is designed with a wavelength-tunable laser element, semiconductor optical amplifier, optical isolator, light intensity variation detector, wavelength dithering generation unit, and feedback control units to modulate the resonator mode and maintain constant output power, allowing for precise wavelength control and stable single-mode emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the length of the optical resonator is increased to narrow the line width, then the line width is narrowed, but the channel spacing becomes narrow and stable single-mode emission becomes difficult to realize
Solution Approach 1:
The patent implements a feedback control system that detects light intensity variations caused by resonator mode wavelength dithering and adjusts the wavelength selection elements to maintain stable single-mode emission. The feedback control unit monitors the output and dynamically corrects wavelength drift, enabling both narrow line width and stable single-mode operation to coexist.
Solution Approach 2:
The patent introduces dynamic wavelength dithering of the resonator mode and dynamic adjustment of wavelength selection elements. By continuously modulating the resonator mode wavelength and adjusting the wavelength selection elements in response, the system adapts to maintain stable single-mode emission while achieving narrow line width, transforming a static problem into a dynamically controlled solution.
2Power
If a semiconductor optical amplifier is used to amplify laser light output from a semiconductor laser, then the laser light is amplified, but accurate wavelength control becomes difficult
Solution Approach 1:
The patent performs wavelength selection and stabilization before the light enters the semiconductor optical amplifier. By pre-adjusting the wavelength selection elements and stabilizing the resonator mode wavelength prior to amplification, the system ensures that the amplified light maintains accurate wavelength control, preventing wavelength drift that would occur during or after amplification.
Solution Approach 2:
The feedback control system monitors wavelength variations and adjusts the wavelength selection elements in real-time, even after amplification by the semiconductor optical amplifier. This continuous feedback mechanism compensates for any wavelength drift introduced during amplification, maintaining accurate wavelength control throughout the entire system.
3Measurement precision
If feedback control is performed on the resonator mode wavelength dithering, then wavelength control is improved, but the variation in intensity may be attenuated by the dithering
Solution Approach 1:
The patent introduces a beam splitter as an intermediary that separates the light path into two channels: one for wavelength control detection and another for intensity variation detection. This allows the feedback control to operate on wavelength dithering while the intensity variations are detected separately without being attenuated by the dithering process, preserving the information needed for both control functions.
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 device enables accurate control of laser wavelength and stable single-mode emission by modulating the resonator mode and maintaining constant output power, overcoming the limitations of narrow channel spacing and amplification challenges.
Implementation Method 1
a wavelength dithering generation unit that generates a resonator mode wavelength dithering to modulate a resonator mode of the optical resonator on a wavelength axis
Implementation Method 2
a semiconductor optical amplifier configured to receive laser light output from the wavelength-tunable laser element and amplify the received laser light
Implementation Method 3
a light intensity variation detector configured to detect variation in intensity of the laser light output from the wavelength-tunable laser element
Data Source
AI summary
A laser device includes a wavelength-tunable laser including plural wavelength selectors in an optical resonator; a semiconductor optical amplifier that amplifies the laser light input thereto; a light intensity variation detector that detects variation in intensity of the laser light output from the wavelength-tunable laser before the laser light is input to the semiconductor optical amplifier; a wavelength dithering generation unit that generates a resonator mode wavelength dithering to modulate a resonator mode of the resonator; a wavelength dithering feedback controller that performs, on the resonator mode wavelength dithering, feedback control based on the variation in intensity detected by the light intensity variation detector; a light intensity detector that detects an intensity of the laser light output from the semiconductor optical amplifier; and a semiconductor optical amplifier feedback controller that performs feedback control on the semiconductor optical amplifier based on the intensity detected by the light intensity detector.