We design and experimentally demonstrate a polarizing beam splitter (PBS) on a silicon-on-insulator (SOI) platform based on an asymmetric directional coupler. The asymmetric directional coupler consists of a regular strip waveguide and a sub-wavelength grating (SWG) waveguide. Engineering the waveguide dispersion via SWG, the phase-matching condition can be satisfied for TM polarization over a broad bandwidth when the waveguide dimensions are optimized. The coupling region of the realized PBS is ∼7.2 µm long. For the fabricated PBS, the polarization extinction ratio (PER) is 10–45 dB and the insertion loss is 0.3–2.5 dB for TM polarization while the PER is 14–22 dB and the insertion loss is < 0.6 dB for TE polarization when operating in the wavelength range of 1460 –1610 nm.
In this paper, we present the design, optimization, and implementation of a sub-wavelength grating (SWG) multi-mode interference coupler (MMI) on the silicon nitride photonic integrated circuit (PIC) platform with a significantly enhanced bandwidth compared to the conventional MMI. We extend the SWG MMI theory, previously presented for the silicon-on-insulator platform, to the Si3N4/SiO2platform. Our approach involves an initial parameter optimization for a non-paired design, followed by a shift to a paired design that offers a smaller footprint and a broader bandwidth. The optimized SWG MMI exhibits a 1 dB bandwidth of 300 nm for both the insertion loss and power imbalance, making it a significant addition to silicon nitride photonics.
more » « less- Award ID(s):
- 2219760
- PAR ID:
- 10493499
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 32
- Issue:
- 6
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 9405
- Size(s):
- Article No. 9405
- Sponsoring Org:
- National Science Foundation
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