Optical Circuit Element With Spot Size Converters
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Solution Overview
Problem
Optical circuit elements, particularly polarization beam splitters, face challenges in minimizing insertion loss and reducing the number of wave plates used, which affects their efficiency and integration in optical communication systems.
Innovation Solution
The design incorporates a Mach-Zehnder interferometer structure with multiple input and output couplers, spot size converters, and strategically placed wave plates in slits to manage polarization splitting, minimizing crosstalk and insertion loss, and optimizing the use of wave plates by using refractive index matching epoxy and specific wave plate orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wave plates are inserted into slits to control polarization phase difference, then polarization beam splitting function is achieved, but insertion loss increases
Solution Approach 1:
The patent introduces spot size converters as intermediary components between the waveguides and slits. These converters gradually transform the mode field diameter, serving as a transition zone that reduces the abrupt refractive index change at the slit interface. This intermediary structure minimizes reflection and scattering losses while maintaining the polarization beam splitting function achieved by the wave plates in the slits.
Solution Approach 2:
The patent employs spot size converters that gradually change the mode field diameter parameter along the propagation direction. By continuously transforming the beam size from a smaller diameter in the waveguide to a larger diameter at the slit, the parameter change reduces impedance mismatch and minimizes insertion loss. The gradual parameter transformation ensures efficient power transmission while maintaining the polarization control function.
2Reliability
If multiple wave plates are used to achieve polarization control, then polarization beam splitting is achieved, but device complexity increases
Solution Approach 1:
The patent combines multiple polarization control functions into a single integrated Mach-Zehnder interferometer structure. Instead of using separate wave plates at different locations, the design merges the polarization splitting and phase control functions into one compact interferometric structure with two symmetric paths, reducing the total number of wave plates required while maintaining full polarization beam splitting capability.
Solution Approach 2:
The Mach-Zehnder interferometer structure serves multiple functions simultaneously: it provides polarization beam splitting, phase control, and intensity modulation all within a single integrated device. The two symmetric paths of the interferometer universally handle both polarization components, allowing one structure to perform what would traditionally require multiple separate components.
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 insertion loss and minimizes the number of wave plates required, enhancing the efficiency and cost-effectiveness of optical circuit elements while maintaining single-mode signal stability and reducing crosstalk, making them suitable for advanced optical communication applications.
Implementation Method 1
The phases of the two optical paths may be controlled by a birefringence of a optical waveguide or a wave plate inserted in the slit of a optical waveguide
Implementation Method 2
a plurality of first spot size converters respectively connected to the first input waveguides, a plurality of second spot size converters connected to the first output waveguides
Implementation Method 3
a refractive index matching epoxy of which hardness is changeable may be filled in the at least one of the first and second slits
Data Source
AI summary
Provided is an optical circuit element, and more particularly, is an optical circuit element that splits one optical signal into two polarization signals, or couples two polarization signals into one optical signal. The optical circuit element includes a plurality of input couplers to which an optical signal is input, a plurality of output couplers from which an optical signal is output, a first path and a second path configured to connect the input couplers and the second couplers to each other, and at least one wave plate.