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Bandwidth Tunable Optical Bandpass Filter Based on Parity-Time Symmetry
Bowen Zhang1, Nuo Chen1, Xinda Lu1
1School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.
Micromachines
|January 21, 2022
Summary
We developed a new tunable optical filter using parity-time (PT) symmetry in coupled microresonators. This breakthrough enables large bandwidth tunability for reconfigurable optical systems.
Area of Science:
- Photonics
- Integrated Optics
- Non-Hermitian Optics
Background:
- Chip-scale tunable optical filters are crucial for reconfigurable wavelength division multiplexing systems, channel routing, and optical switching.
- Existing tunable filters often face limitations in bandwidth tunability and integration complexity.
Purpose of the Study:
- To propose and demonstrate a novel scheme for bandwidth tunable band-pass filters.
- To leverage parity-time (PT) symmetry and coupled microresonators for enhanced tunability.
Main Methods:
- Utilizing a parity-time (PT) symmetric coupled microresonator system.
- Tuning the relative resonant frequency between coupled rings to achieve bandwidth tunability.
- Exploiting the exceptional point (EP) in PT symmetric systems.
Main Results:
- Demonstrated a proof-of-concept device with a bandwidth tuning range from 21 GHz to 49 GHz.
- Achieved an extinction ratio greater than 15 dB.
- Theoretical analysis indicated bandwidth tuning range depends on intrinsic loss and loss contrast.
Conclusions:
- The PT symmetric coupled microresonator design offers a distinct route for realizing tunable band-pass filters.
- This approach provides new avenues for non-Hermitian light manipulation in integrated photonic devices.
- Discrepancies between theory and experiment were attributed to non-optimized coupling and fabrication errors.
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