One-chip integration of optical correlator based on slow-light devices

Shun Kinugasa,Naoya Yazawa,Hiroyuki Ito,Norihiro Ishikura,Toshihiko Baba

doi:10.1364/oe.23.020767

Abstract

We propose and demonstrate an on-chip optical correlator, in which two types of photonic crystal slow-light waveguides are integrated and operated as an optical delay scanner and a two-photon-absorption photodetector. The footprint of the device, which was fabricated using a CMOS-compatible process, was 1.0 × 0.3 mm(2), which is substantially smaller than that of conventional optical correlators with free-space optics. We observed optical pulses using this device and confirmed the correspondence of pulse waveforms with those observed using a commercial correlator when the pulse width was 5-7 ps. This device will achieve one-chipping of an optical correlator and related measurement instruments.

Highlights

An optical correlator is widely used to observe short optical pulses with a time duration of less than 10 ps, which is difficult for optoelectronic devices
Some methods other than optical correlators exist for measuring short optical pulses, which include frequency-resolved optical gating (FROG) [8, 9], simplified FROG [10], digital holography [11], and near-field scanning microscopy [12], among others
We have studied an Si photonic crystal waveguide (PCW) fabricated by such a process and its slow-light generation, demonstrating tunable delays [13, 14] and a two-photon-absorption photodetector (TPA-PD) [15] at telecom wavelengths

Summary

Introduction

An optical correlator is widely used to observe short optical pulses with a time duration of less than 10 ps, which is difficult for optoelectronic devices It fundamentally comprises an optical delay scanner and a nonlinear photodetector. Some methods other than optical correlators exist for measuring short optical pulses, which include frequency-resolved optical gating (FROG) [8, 9], simplified FROG [10], digital holography [11], and near-field scanning microscopy [12], among others. All these methods involve large systems with free-space optics. We propose and demonstrate an on-chip optical correlator in which the two basic components are integrated monolithically

Design

Fabrication

Auto-correlation waveform

Conclusion