Semiconductor Laser Device with Integrated Optical Feedback
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Solution Overview
Problem
Semiconductor lasers face challenges in narrowing spectral linewidth for mid- and long-distance optical communications and sensing due to high phase noise and complexity in control circuits, particularly in external cavity type lasers and DFB lasers, where maintaining uniformity and stability is difficult.
Innovation Solution
A semiconductor laser device with an integrated optical-feedback lightwave circuit on a single substrate, using a DFB or DBR laser array and optical multiplexer, where part of the output light is fed back to the laser, stabilizing the oscillation and allowing for wavelength tunability without precise filter adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external cavity type laser is used to narrow spectral linewidth, then spectral linewidth is narrowed to about 10 kHz, but device complexity increases due to multiple components and complicated control circuits
Solution Approach 1:
The patent integrates the semiconductor laser, external cavity resonator, and wavelength selection filter into a single compact device. The resonator is formed by bonding a substrate with a reflector to the laser chip, and the filter is integrated on the same substrate, eliminating the need for separate components and reducing assembly complexity while achieving narrow spectral linewidth of about 10 kHz
Solution Approach 2:
The substrate serves multiple functions: it acts as the resonator cavity, provides mechanical support, and integrates the wavelength selection filter. The reflector on the substrate provides both optical feedback for lasing and wavelength selection, combining multiple functions into single elements to reduce overall device complexity
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 configuration achieves a significantly narrowed spectral linewidth, enhancing controllability and stability, making it suitable for digital coherent communications and optical sensing with improved wavelength tunability and reduced manufacturing complexity.
Implementation Method 1
part of output light from a semiconductor laser is returned to the semiconductor laser by using an optical resonator for optical feedback
Implementation Method 2
a DFB or DBR laser array and optical multiplexer where part of the output light is fed back to the laser
Data Source
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AI summary
An external cavity type laser has a configuration of narrowing a spectral linewidth in a semiconductor laser up to about 10 kHz, but since multiple components are required and they need to be assembled with high precision, there has been a problem that their control circuits are complicated. A configuration of a DFB laser-based wavelength tunable laser is well known, but long resonators have difficulty in forming uniform resonators due to production variations, thereby inducing limitation in narrowing the spectral linewidth in the DFB laser-based wavelength tunable laser as well. In the semiconductor laser device of the present invention, a semiconductor laser that oscillates in a single mode and a low-loss lightwave circuit using SiO2 glass are arranged on the common substrate. The lightwave circuit is configured such that part of output light from the semiconductor laser propagates through a certain length of an optical path, and then is reflected by a reflector and is fed back to the semiconductor laser. Output light from the semiconductor laser and an input waveguide of the lightwave circuit can also be configured to be optically connected directly to each other. The present invention can provide a compact laser device with a narrowed spectral linewidth and stable wavelength controllability.