Semiconductor Laser Resonator Layout Using Diffraction Grating Feedback
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Solution Overview
Problem
Existing semiconductor laser devices face challenges in achieving phase matching between the oscillation mode of the resonator and the semiconductor laser, requiring precise position adjustment of the cleaved surface, which increases device size and complexity, and necessitate curved waveguides that widen the chip.
Innovation Solution
An optical semiconductor device with a semiconductor laser and a reflecting portion forming a resonator, utilizing a diffraction grating for light feedback, eliminating the need for phase adjustment regions and curved waveguides, and allowing for a smaller device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaved surface is used as the reflecting portion, then light feedback can be achieved, but phase matching requires precise position adjustment which increases device size
Solution Approach 1:
The patent replaces the mechanical position adjustment system with an optical diffraction grating system. Instead of mechanically adjusting the cleaved surface position to achieve phase matching, the diffraction grating provides fixed wavelength-selective feedback that inherently satisfies phase matching conditions, eliminating the need for mechanical phase adjustment mechanisms and reducing device size.
Solution Approach 2:
The patent changes the reflection mechanism from geometric reflection (cleaved surface) to diffraction-based selective feedback (diffraction grating). This parameter change in the optical feedback mechanism allows wavelength-selective feedback without requiring precise mechanical positioning, thereby resolving the contradiction between phase matching reliability and device size.
2Reliability
If a curved waveguide is formed to guide light to the cleaved surface, then light feedback is achieved, but the curvature radius increases chip width
Solution Approach 1:
The patent replaces the curved waveguide mechanical routing with a planar diffraction grating structure. The diffraction grating provides the necessary optical feedback path in a compact, planar configuration, eliminating the need for large-curvature-radius waveguides and reducing chip width while maintaining effective light feedback.
Solution Approach 2:
The patent transitions from three-dimensional curved waveguide routing to two-dimensional planar diffraction grating structure. This dimensional change allows optical feedback to be achieved in a compact planar layout without requiring large curvature radii, thereby reducing chip width while maintaining feedback functionality.
3Manufacturing precision
If phase adjustment region is added to adjust oscillation mode phase, then phase matching can be achieved, but device complexity and size increase
Solution Approach 1:
The patent replaces the phase adjustment region (a complex mechanical adjustment structure) with a diffraction grating that provides inherent phase matching through its diffraction physics. The grating equation naturally provides the correct phase relationship for wavelength-selective feedback, eliminating complex phase adjustment mechanisms and reducing device complexity.
Solution Approach 2:
The diffraction grating performs self-adjustment through its inherent diffraction physics. The grating automatically provides wavelength-selective feedback with correct phase matching based on the diffraction condition, without requiring external phase adjustment mechanisms. This self-service property reduces device complexity while maintaining manufacturing precision.
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 enables a smaller optical semiconductor device with improved spectral line width reduction and reduced complexity, achieving phase matching without the need for precise position adjustments or curved waveguides, while maintaining high reflection efficiency.
Implementation Method 1
the reflecting portion includes a diffraction grating that reflects the third output light amplified by the optical amplifier
Implementation Method 2
the semiconductor laser and the reflecting portion form a resonator
Implementation Method 3
a second waveguide portion including an optical amplifier amplifying the third output light
Data Source
AI summary
An optical semiconductor device according to the present disclosure includes a semiconductor substrate, at least one semiconductor laser provided on the semiconductor substrate, an optical multiplexer/demultiplexer circuit provided on the semiconductor substrate, multiplexing or demultiplexing first output light of the semiconductor laser and outputting second output light and third output light, a first waveguide portion provided on the semiconductor substrate, and outputting the second output light from an end face of the semiconductor substrate, and a second waveguide portion including an optical amplifier amplifying the third output light and a reflecting portion and provided on the semiconductor substrate, wherein the reflecting portion includes a diffraction grating that reflects the third output light amplified by the optical amplifier to feed back to the semiconductor laser via the optical amplifier and the optical multiplexer/demultiplexer circuit, and the semiconductor laser and the reflecting portion form a resonator.