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Mode conversion and birefringence adjustment by focused-ion-beam etching for slanted rib waveguide walls
Po Shan Chan1, H K Tsang, C Shu
1Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. pschan@ee.cuhk.edu.hk
Optics Letters
|November 1, 2003
Summary
Focused-ion-beam (FIB) etching precisely trims silicon-on-insulator rib waveguides. This method modifies differential group delay and achieves efficient TE to TM mode conversion.
Area of Science:
- Photonics
- Materials Science
- Nanotechnology
Background:
- Silicon-on-insulator (SOI) waveguides are crucial for integrated photonics.
- Controlling polarization and delay is essential for advanced photonic devices.
- Focused-ion-beam (FIB) offers high-precision nanofabrication capabilities.
Purpose of the Study:
- To investigate the use of FIB etching for modifying waveguide properties.
- To introduce TE to TM mode conversion in SOI rib waveguides.
- To analyze the impact of slanted rib waveguide walls on differential group delay.
Main Methods:
- Fabrication of single-mode SOI rib waveguides with FIB-trimmed slanted walls.
- Characterization of waveguides with varying lengths of 45-degree slant angles.
- Measurement of differential group delays and TE to TM mode conversion efficiency.
Main Results:
- FIB trimming successfully modified the waveguide geometric cross-section.
- Differential group delay was altered by the slanted rib waveguide walls.
- TE to TM mode conversion was achieved through precise FIB modification.
Conclusions:
- FIB etching is an effective technique for tuning waveguide dispersion and polarization properties.
- The geometric modification of rib waveguides using FIB enables controlled mode conversion.
- This approach provides a pathway for developing novel photonic integrated circuits.