Dual-Wavelength Semiconductor Laser Locking to a Shared Resonance
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Solution Overview
Problem
Existing lasers, such as HeNe lasers, have limited lifespans and are costly to replace in applications like integrated lithography, and semiconductor lasers lack dual wavelength stabilization and accuracy for telecom and datacom applications.
Innovation Solution
A dual-wavelength stabilized semiconductor laser using an optical resonance mechanism, employing an absorptive optical resonator or high-Q optical ring resonator, with a feedback control circuit to maintain precise wavelength stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Helium-Neon laser is used for frequency stabilization, then wavelength accuracy is improved, but device lifetime deteriorates (only 3 years) and replacement cost increases
Solution Approach 1:
The patent replaces the expensive, short-lived HeNe laser with a semiconductor laser that can be stabilized to achieve comparable wavelength accuracy. Semiconductor lasers are more durable, have longer lifetimes, and are cost-effective for replacement, while maintaining the required stabilization performance through integration with wavemeters and control systems.
2Measurement precision
If a precision HeNe laser is used, then wavelength stability is improved, but adaptability deteriorates (visible wavelength band outside telecom and datacom spectra)
Solution Approach 1:
The patent transitions from HeNe lasers operating in the visible band to semiconductor lasers operating in the infrared telecom and datacom bands (1550 nm, 1310 nm, 850 nm). This parameter change in operating wavelength enables integration with modern optical communication systems while maintaining wavelength stability through stabilization techniques involving wavemeters and feedback control.
3Device complexity
If a single-mode semiconductor laser is used for stabilization, then device complexity is reduced, but measurement precision deteriorates (cannot provide dual wavelength for displacement measurement)
Solution Approach 1:
The patent employs multiple separate semiconductor lasers, each stabilized to a specific wavelength (e.g., 1550 nm and 1310 nm), rather than attempting to stabilize a single laser to multiple wavelengths. This segmentation approach simplifies the stabilization of each individual laser while providing the dual-wavelength capability needed for displacement measurements through techniques like heterodyne detection.
4Adaptability or versatility
If semiconductor lasers with gas resonance stabilization are used, then telecom and datacom integration is improved, but measurement precision deteriorates (insufficiently accurate output signals and requirement for dither signal)
Solution Approach 1:
The patent implements feedback control systems using wavemeters to monitor the actual wavelength of semiconductor lasers and adjust them accordingly. This closed-loop feedback stabilization achieves higher wavelength accuracy than gas resonance methods and eliminates the need for dither signals, while maintaining compatibility with telecom and datacom applications through integration with optical networks.
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
Provides accurate and stable dual-wavelength output with high precision, suitable for applications like displacement measurement and spectral analysis, overcoming the limitations of existing lasers.
Implementation Method 1
an optical resonator connected to the optical coupler and adapted to attenuate the third optical signal at a characteristic wavelength
Data Source
AI summary
An apparatus for providing two wavelengths (λ and λ+Δλ) from a laser that are locked to the same resonance. The apparatus includes an optical resonator connected to the optical coupler and adapted to attenuate the third optical signal at a characteristic wavelength. The apparatus also includes a feedback control circuit configured to change properties of the laser to be locked until an error signal indicative of the difference between the characteristic wavelength and the wavelength of the laser is offset by approximately Δλ/2. The apparatus may be a photonic integrated circuit (PIC), and may have the feedback control circuit off-chip.