On-Chip Polarization Controller via Mode Conversion
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Solution Overview
Problem
Current polarization controllers are large, have low isolation, and are inconvenient to adjust, with limited bandwidth and complex manufacturing processes, making them unsuitable for dynamic polarization control in integrated optical systems.
Innovation Solution
An on-chip polarization controller using mode hybridization and phase shifters for dynamic adjustment, incorporating an input and output polarization-dependent mode converters, a multi-mode Mach-Zehnder interferometer, and phase shifters to achieve high extinction ratio, low insertion loss, and large bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional polarization controllers are used, then polarization control function is achieved, but the device volume is large and structure is complex
Solution Approach 1:
The patent replaces mechanical polarization controllers with an on-chip integrated optical polarization controller. The mechanical adjustment structure is substituted by waveguide-based mode converters and phase shifters fabricated on a semiconductor substrate, eliminating the need for bulk optical components and mechanical adjustment mechanisms while achieving compact integration.
Solution Approach 2:
The patent merges multiple polarization control functions (mode conversion, phase shifting, polarization state adjustment) into a single integrated on-chip device. The input mode converter, phase shifters, and output mode converter are combined on one chip to achieve complete polarization control in a unified compact structure.
2Reliability
If conventional polarization controllers are used, then polarization control is achieved, but the isolation is low and adjustment is inconvenient
Solution Approach 1:
The patent implements dynamic polarization control through electrically controllable phase shifters that can adjust the relative phase between TE and TM modes in real-time. This enables dynamic adjustment of polarization states without mechanical movement, improving both convenience and reliability.
Solution Approach 2:
Manual mechanical adjustment is replaced by electrical control of phase shifters. The polarization state is adjusted by applying voltages to the phase shifters, which change the optical path difference between modes electrically, eliminating mechanical adjustment mechanisms and improving reliability.
3Adaptability or versatility
If existing dynamic polarization controllers are used, then dynamic polarization adjustment is achieved, but the bandwidth is small and manufacturing process is complex
Solution Approach 1:
The patent achieves broad bandwidth by designing waveguide structures and mode converters that operate effectively across a wide wavelength range. The adiabatic mode conversion design maintains low loss and high efficiency across different wavelengths, while the phase shifters are designed to provide sufficient phase control range over the entire operational bandwidth.
Solution Approach 2:
The patent uses standard semiconductor fabrication processes to manufacture the on-chip polarization controller, replacing complex assembly processes with scalable photolithography and etching techniques. This simplifies manufacturing while enabling mass production and improving consistency.
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 provides a compact, high-extinction-ratio, low-crosstalk, large-bandwidth polarization controller suitable for optical fiber and quantum communication systems, with a large manufacturing tolerance and flexible polarization state conversion.
Implementation Method 1
uses mode hybridization conversion between TM0 and TE1 modes
Implementation Method 2
utilizes an on-chip polarization-dependent mode converter to simultaneously achieve lossless adiabatic mode evolution between TE0 modes and mode hybridization conversion between TM0 and TE1 modes
Implementation Method 3
uses a phase shifter to control intensity and a phase relationship for the TE0 and the TM0 in a main waveguide
Implementation Method 4
achieve lossless adiabatic mode evolution between TE0 modes
Data Source
AI summary
A polarization controller based on on-chip mode conversion is provided. An input end-face coupler is connected to an input end of an input polarization-dependent mode converter through an input phase shifter. An output end of the input polarization-dependent mode converter is connected to an input end of a multi-mode 1×1 Mach-Zehnder interferometer (MZI), and an output end of the multi-mode 1×1 MZI is connected to an input end of an output polarization-dependent mode converter. An output end of the output polarization-dependent mode converter is connected to an output end-face coupler through an output phase shifter. The input end and the output end of the multi-mode 1×1 MZI are respectively connected to the input polarization-dependent mode converter and the output polarization-dependent mode converter to form a polarization insensitive beam splitting structure. The polarization controller can convert any two arbitrary polarization states, and has a compact structure and a large bandwidth.