Semiconductor Laser Slot Filled With Reflective Material
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Solution Overview
Problem
Prior art semiconductor lasers experience destructive interference from scattering and reflection processes, which hinder optimal single mode emission.
Innovation Solution
A semiconductor laser with a slot filled with a reflective material having a large imaginary index relative to the laser cavity material, positioned such that the abrupt interfaces of the slot features coincide with nodes or anti-nodes of the electric field to optimize scattering and reflection effects, respectively, to achieve constructive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slot is etched in the ridge waveguide to provide optical feedback, then single longitudinal mode emission is achieved, but scattering and reflection processes interfere destructively causing increased cavity losses
Solution Approach 1:
The patent converts the harmful scattering and reflection processes into beneficial effects by filling the slot with reflective material. The reflective material transforms what would be destructive scattering into constructive reflection, where the reflected light reinforces the desired mode rather than causing losses. This resolves the contradiction by turning the harmful optical feedback into a beneficial mechanism that reduces cavity losses while maintaining single mode emission.
Solution Approach 2:
The patent changes the optical parameters of the slot by filling it with material having a large imaginary index. This parameter change transforms the slot from a scattering center into a reflective element, fundamentally altering how light interacts with the slot structure. The large imaginary index material provides the necessary reflection coefficient to convert destructive scattering into constructive reflection, thereby reducing cavity losses.
2Loss of energy
If the slot interfaces are positioned to optimize reflection, then constructive interference is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The use of material with a large imaginary index fundamentally changes the optical parameters of the slot interface. This parameter change makes the system less sensitive to precise positioning because the strong reflection effect dominates over the phase variations caused by positioning tolerances. The large imaginary index provides a robust reflection mechanism that is more tolerant to manufacturing variations.
Solution Approach 2:
The patent applies local quality by concentrating the optical feedback mechanism at the specific location of the slot interfaces within the cavity. By providing strong reflection at these localized positions, the system achieves constructive interference without requiring precise positioning throughout the entire device. The local quality of the reflective material at the slot interfaces is what determines the overall performance.
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 reduces cavity losses and enhances the spectral performance by counteracting the effects of scattering and reflection, leading to improved single mode emission.
Implementation Method 1
a slot having an interface, characterised in that the slot is substantially filled with a reflective material having a large imaginary index relative to the laser cavity material
Implementation Method 2
the scattering and reflection processes interfere constructively
Data Source
AI summary
The present application relates to a semiconductor laser, in particular such a laser which operates with substantially single longitudinal mode emission. The laser comprising a laser cavity, the laser further comprising a slot having an interface, characterized in that the slot is substantially filled with a reflective material having a large imaginary index relative to the laser cavity material. The interfaces of the slot may be inclined or may have a step for introducing a quarter wave phase shift.