Asymmetric, non-uniform 3-dB directional coupler with 300-nm bandwidth and a small footprint

Hamed Nikbakht, Mohammad Talebi Khoshmehr, Bob van Someren, Dieter Teichrib, Manfred Hammer, Jens Förstner, B. Imran Akca*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

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Abstract

Here we demonstrate a new, to the best of our knowledge, type of 3-dB coupler that has an ultra-broadband operational range from 1300 to 1600nm with low fabrication sensitivity. The overall device size is 800 μm including in/out S-bend waveguides. The coupler is an asymmetric non-uniform directional coupler that consists of two tapered waveguides. One of the coupler arms is shifted by 100 μm in the propagation direction, which results in a more wavelength-insensitive 3-dB response compared to a standard (not shifted) coupler. Moreover, compared to a long adiabatic coupler, we achieved a similar wavelength response at a 16-times-smaller device length. The couplers were fabricated using the silicon nitride platform of Lionix International.We also experimentally demonstrated an optical switch that is made by using two of these couplers in a Mach-Zehnder interferometer configuration. According to experimental results, this optical switch exhibits -10 dB of extinction ratio over the 1500-1600nm wavelength range. Our results indicate that this new type of coupler holds great promise for various applications, including optical imaging, telecommunications, and reconfigurable photonic processors where compact, fabrication-tolerant, and wavelength-insensitive couplers are essential.

Original languageEnglish
Pages (from-to)207-210
Number of pages4
JournalOptics Letters
Volume48
Issue number2
Early online date2 Jan 2023
DOIs
Publication statusPublished - 15 Jan 2023

Bibliographical note

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© 2023 Optica Publishing Group.

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