Wavelength Tunable Laser Using Group III-V Grating
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Solution Overview
Problem
Wavelength tunable laser devices using SOI substrates with waveguides and resonators face challenges due to two-photon absorption and refractive index fluctuations, leading to unstable wavelength tuning and increased spectral linewidth.
Innovation Solution
A wavelength tunable laser device is developed with a silicon substrate and bonded semiconductor elements, where a second semiconductor element with a grating formed from a group III-V compound semiconductor is used to select the wavelength, minimizing two-photon absorption and stabilizing tunable laser characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon waveguide and resonator are used for wavelength selection, then the device can be manufactured with high precision using standard SOI technology, but two-photon absorption occurs causing refractive index fluctuations and unstable wavelength tuning
Solution Approach 1:
The patent changes the material parameter of the wavelength selection component from silicon to group III-V compound semiconductor. This material substitution fundamentally alters the optical properties, eliminating two-photon absorption while maintaining the wavelength selection function through grating structures, thus resolving the contradiction between manufacturing precision and wavelength tuning stability
Solution Approach 2:
The patent creates a hybrid structure combining silicon waveguide (for light propagation) with group III-V compound semiconductor (for wavelength selection). This composite approach allows each material to perform its optimal function: silicon provides low-loss light guidance while the group III-V material provides stable wavelength selection without two-photon absorption
2Device complexity
If a silicon resonator is used to select wavelength, then the device structure can be simplified, but spectral linewidth increases and wavelength selection precision deteriorates
Solution Approach 1:
The patent changes the material composition parameter from pure silicon resonator to group III-V compound semiconductor grating. This material change enables precise wavelength selection through diffraction grating physics rather than resonant cavity physics, achieving narrow spectral linewidth while maintaining relatively simple device structure
Solution Approach 2:
The patent replaces the resonant cavity mechanism (which relies on optical feedback and standing waves) with a diffraction grating mechanism (which relies on constructive interference from periodic structures). This substitution achieves wavelength selection with narrower linewidth and reduced sensitivity to fabrication tolerances
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 achieves stable wavelength tuning and narrow spectral linewidth by reducing two-photon absorption, allowing for precise control of the oscillation wavelength and enhancing the device's performance.
Implementation Method 1
a second semiconductor element including a grating formed of a second group III-V compound semiconductor. The grating selects a wavelength of the light
Data Source
AI summary
A wavelength tunable laser device includes a substrate including silicon, the substrate having a waveguide, a first semiconductor element bonded to the substrate, the first semiconductor element including an active layer of a group III-V compound semiconductor, and a second semiconductor element bonded to the substrate, the second semiconductor element facing to the first semiconductor element in a direction along which light emitted from the first semiconductor element propagates, the second semiconductor element including a grating formed of a group III-V compound semiconductor. The grating selects a wavelength of light.