Local-field engineering in slot waveguide for fabricating on-chip Bragg grating filters with high reflectivity across a flat broadband.
Opt Express
; 32(3): 4684-4697, 2024 Jan 29.
Article
in En
| MEDLINE
| ID: mdl-38297663
ABSTRACT
On-chip Bragg gratings with high reflectivities have been found to have widespread applications in filters, resonators, and semiconductor lasers. However, achieving strong Bragg reflections with flat response across a broad bandwidth on the popular 220â
nm silicon-on-insulator (SOI) platform still remains a challenge. In this paper, such a high performance device is proposed and fabricated, which is based on a slot waveguide with gratings etched on the inner sidewalls of the slot. By manipulating the local field in the slot region using a chirped and tapered grating-based mode transition, the device achieves a flat response with ultra-high reflection and low transmission for the TE mode across a broad operating bandwidth. Leveraging the ultra-high birefringence of the SOI waveguide, the device functions both as a TE slot waveguide reflector and a TM pass polarizer. Simulation results demonstrate that the device exhibits an ultra-high rejection of more than 50â
dB and a reflectivity exceeding 0.99 for the TE mode across a 91â
nm wavelength range, while maintaining a high transmittance of larger than 0.98 for the TM mode. Experimental results validate that the device performance is consistent with the simulation results. A fabricated device based on such a gratings exhibits a low insertion loss (<0.8â
dB) and high polarization extinction ratio (>30â
dB) over 100â
nm bandwidth (1484â
nm-1584â
nm), demonstrating that the performance of the present design is competitive with that of the state-of-the-art SOI Bragg gratings.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Opt Express
Journal subject:
OFTALMOLOGIA
Year:
2024
Document type:
Article
Country of publication: