Germanium-on-silicon mid-infrared grating couplers with low-reflectivity inverse taper excitation

被引：45

作者：

Alonso-Ramos, Carlos ^{[1
]}

Nedeljkovic, Milos ^{[2
]}

Benedikovic, Daniel ^{[1
]}

Penades, Jordi Soler ^{[2
]}

Littlejohns, Callum G. ^{[2
,3
]}

Khokhar, Ali Z. ^{[2
]}

Perez-Galacho, Diego ^{[1
]}

Vivien, Laurent ^{[1
]}

Cheben, Pavel ^{[4
]}

Mashanovich, Goran Z. ^{[2
]}

机构：

[1] Univ Paris Saclay, Univ Paris 11, Ctr Nanosci & Nanotechnol, CNRS,Orsay C2N, F-91405 Orsay, France

[2] Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England

[3] Nanyang Technol Univ, Silicon Ctr Excellence, 50 Nanyang Ave, Singapore 639798, Singapore

[4] CNR, Ottawa, ON K1A 0R6, Canada

来源：

OPTICS LETTERS | 2016年 / 41卷 / 18期

基金：

英国工程与自然科学研究理事会; 新加坡国家研究基金会;

关键词：

WAVE-GUIDE; CASCADE LASERS; DESIGN; SI;

D O I：

10.1364/OL.41.004324

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

A broad transparency range of its constituent materials and compatibility with standard fabrication processes make germanium-on-silicon (Ge-on-Si) an excellent platform for the realization of mid-infrared photonic circuits. However, the comparatively large Ge waveguide thickness and its moderate refractive index contrast with the Si substrate hinder the implementation of efficient fiber-chip grating couplers. We report for the first time, to the best of our knowledge, a single-etch Ge-on-Si grating coupler with an inversely tapered access stage, operating at a 3.8 mu m wavelength. Optimized grating excitation yields a coupling efficiency of -11 dB (7.9%), the highest value reported for a mid-infrared Ge-on-Si grating coupler, with reflectivity below -15 dB (3.2%). The large periodicity of our higher-order grating design substantially relaxes the fabrication constraints. We also demonstrate that a focusing geometry allows a 10-fold reduction in inverse taper length, from 500 to 50 mu m. (C) 2016 Optical Society of America

引用

页码：4324 / 4327

页数：4

共 24 条

[1] Single-etch grating coupler for micrometric silicon rib waveguides [J].