Monolithic Optical Gate Switch with Quantum Well Phase Modulation
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Solution Overview
Problem
Existing optical gate switches with spatial optical systems face challenges in miniaturization and stability due to large size, environmental sensitivity, and low optical coupling efficiency between silicon wire waveguides and group III-V semiconductor waveguides, leading to increased optical coupling losses and decreased signal-to-noise ratio.
Innovation Solution
A monolithic integrated optical gate switch is developed, featuring a Michelson interferometer with a quantum well core layer and a variable light intensity attenuation unit, incorporating a phase modulation unit and anti-reflective films to optimize light balance and reduce absorption losses, and using quantum well intermixing to shorten the absorption edge wavelength and enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spatial optical system with large-size interferometer is used, then the optical gate switch can be fabricated with existing technologies, but the device size becomes large and environmental stability deteriorates
Solution Approach 1:
The patent combines the interferometer and quantum well phase modulation unit into a monolithic integrated structure on a single semiconductor substrate. This merging eliminates the need for separate optical components and their interconnections, achieving miniaturization while maintaining environmental stability through monolithic integration.
Solution Approach 2:
The patent replaces the mechanical/spatial optical system with an integrated photonic circuit system. By using waveguide-based optical paths instead of free-space optics, the system achieves compact size while maintaining interferometric functionality through controlled phase modulation in the waveguide.
2Ease of manufacture
If silicon wire waveguides are coupled with group III-V semiconductor waveguides, then the optical gate switch can be integrated, but optical coupling losses increase and signal-to-noise ratio decreases
Solution Approach 1:
The patent uses homogeneous group III-V semiconductor materials for both the waveguide and quantum well layers, ensuring material compatibility and minimizing optical coupling losses. The consistent material system allows for efficient light transmission without the losses associated with interfacing dissimilar materials like silicon and group III-V semiconductors.
3Ease of operation
If TM polarization control light is propagated through the optical waveguide, then phase modulation is generated, but absorption loss occurs
Solution Approach 1:
The patent employs quantum well structures with specific intersubband transitions that selectively absorb TM-polarized control light while being transparent to TE-polarized signal light. This local quality differentiation allows the same waveguide to perform both phase modulation (via TM absorption) and low-loss signal transmission (via TE transparency) simultaneously.
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 a high degree of environmental stability and miniaturization, ensuring sufficient signal-to-noise ratio and reducing optical losses, thereby improving the performance and practicality of the optical gate switch.
Implementation Method 1
the optical excitation of an intersubband transition of an InGaAs/AlAsSb semiconductor quantum well by TM polarization light causes an occurrence of a phase modulation effect with response speed of a few picoseconds with respect to TE polarization light without absorption loss
Implementation Method 2
When TM polarization control light is propagated through the optical waveguide, it is absorbed by the intersubband transition. Thus, a refractive index of the quantum well is changed and a phase modulation is generated with respect to TE polarization signal light.
Data Source
AI summary
An object of the present invention is to realize an optical gate switch of a monolithic integration type which can avoid problems of losses caused by light coupling of a phase modulation unit to a interferometer optical circuit unit, and can be minimized by integration. The optical gate switch according to the present invention includes an optical waveguide wafer in which a quantum well having a phase modulation effect which is generated by an intersubband transition is set as a core layer; a Michelson interferometer formed on the optical waveguide wafer; and a variable light intensity attenuation unit adjusting a light balance of an interferometer in one of reflection side arms of the Michelson interferometer reflection.