Low-loss multilevel operation using lossy PCM-integrated silicon photonics

Fuente: arXiv
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Hauptverfasser: Chen, Rui, Tara, Virat, Dutta, Jayita, Fang, Zhuoran, Zheng, Jiajiu, Majumdar, Arka
Format: Preprint
Veröffentlicht: 2024
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author Chen, Rui
Tara, Virat
Dutta, Jayita
Fang, Zhuoran
Zheng, Jiajiu
Majumdar, Arka
author_facet Chen, Rui
Tara, Virat
Dutta, Jayita
Fang, Zhuoran
Zheng, Jiajiu
Majumdar, Arka
contents Chalcogenide phase-change materials (PCMs) offer new paradigms for programmable photonic integrated circuits (PICs) thanks to their zero static energy and significant refractive index contrast. However, prototypical PCMs, such as GeSbTe (GST), are lossy in their crystalline phase, albeit transparent in the amorphous state. Moreover, electrically switching PCMs to intermediate states is a stochastic process, limiting programming accuracy. As a result, achieving both low-loss and deterministic multi-level operation with GST remains challenging. Although low-loss PCMs, such as Sb2S3 and Sb2Se3, have been discovered in recent years, they are much less technologically mature. In this work, we propose a design with multiple GST segments to overcome the challenge of deterministic multilevel operation. GST segments are individually controlled by interleaved silicon PIN diode heaters in a binary but reliable fashion, and multiple levels are encoded in their phase sequence. A 1 x 1 programmable unit with two unequal GST segments is experimentally demonstrated, showcasing four distinct operation levels and negligible thermal crosstalk with only one pair of metal contacts. We then extend the design to 1 x 2 and 2 x 2 programmable units. For the 2 x 2 programmable unit design, we propose a phase-detuned three-waveguide directional coupler structure to mitigate the absorption and radiation loss, showing < -1.2 dB loss and three splitting ratios. Our work provides a new path toward low-loss and multi-level optical switches using lossy PCMs.
format Preprint
id arxiv_https___arxiv_org_abs_2402_08803
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Low-loss multilevel operation using lossy PCM-integrated silicon photonics
Chen, Rui
Tara, Virat
Dutta, Jayita
Fang, Zhuoran
Zheng, Jiajiu
Majumdar, Arka
Optics
Applied Physics
Chalcogenide phase-change materials (PCMs) offer new paradigms for programmable photonic integrated circuits (PICs) thanks to their zero static energy and significant refractive index contrast. However, prototypical PCMs, such as GeSbTe (GST), are lossy in their crystalline phase, albeit transparent in the amorphous state. Moreover, electrically switching PCMs to intermediate states is a stochastic process, limiting programming accuracy. As a result, achieving both low-loss and deterministic multi-level operation with GST remains challenging. Although low-loss PCMs, such as Sb2S3 and Sb2Se3, have been discovered in recent years, they are much less technologically mature. In this work, we propose a design with multiple GST segments to overcome the challenge of deterministic multilevel operation. GST segments are individually controlled by interleaved silicon PIN diode heaters in a binary but reliable fashion, and multiple levels are encoded in their phase sequence. A 1 x 1 programmable unit with two unequal GST segments is experimentally demonstrated, showcasing four distinct operation levels and negligible thermal crosstalk with only one pair of metal contacts. We then extend the design to 1 x 2 and 2 x 2 programmable units. For the 2 x 2 programmable unit design, we propose a phase-detuned three-waveguide directional coupler structure to mitigate the absorption and radiation loss, showing < -1.2 dB loss and three splitting ratios. Our work provides a new path toward low-loss and multi-level optical switches using lossy PCMs.
title Low-loss multilevel operation using lossy PCM-integrated silicon photonics
topic Optics
Applied Physics
url https://arxiv.org/abs/2402.08803