Design of an ultra-compact graphene-based integrated microphotonic tunable delay line.

Giuseppe Brunetti,Donato Conteduca,Mario N Armenise,Francesco Dell’Olio,Caterina Ciminelli

doi:10.1364/oe.26.004593

Abstract

The design of a continuously tunable optical delay line based on a compact graphene-based silicon Bragg grating is reported. High performance, in terms of electro-optical switching time (tswitch < 8 ns), delay range (Δτ = 200 ps), and figure of merit FOM = Δτ/A = 1.54x105 ps/mm2, has been achieved with an ultra-compact device footprint (A ~1.3 x 10-3 mm2), so improving the state-of-the-art of integrated optical delay lines. A continuous and complete tunability of the delay time can be achieved with a very low delay loss ( = 0.03 dB/ps) and a weak power consumption ( = 0.05 mW/ps). A flat bandwidth B = 1.19 GHz has been calculated by exploiting the slow-light effect in the device. This performance makes the proposed optical delay line suitable for several applications in Microwave Photonics (MWP), such as beamsteering/beamforming, for which large delay range, flat and wide bandwidth and small volume are required.

Highlights

Integrated optical delay lines represent a key element in systems for processing and controlling optical signals
The optical beamforming of wideband Phased Array Antennas (PAAs) for telecom and radar payloads in satellite applications represents a promising application in Microwave Photonics (MWP)
The best performance for this class of devices has been obtained with Bragg gratings [13], Photonic Crystal Waveguides (PhCWs) [14] and Ring Resonators (RRs) [15,16,17]

Summary

Introduction

Integrated optical delay lines represent a key element in systems for processing and controlling optical signals. The best performance for this class of devices has been obtained with Bragg gratings [13], Photonic Crystal Waveguides (PhCWs) [14] and Ring Resonators (RRs) [15,16,17] These devices have a simple structure, together with a room-temperature operation, an intrinsic compromise between the maximum delay time, the optical bandwidth and the footprint is necessary. A continuously tunable optical delay line, based on a ring resonator array and a Mach-Zehnder interferometer switch array was proposed [15], with a continuous delay range of few nanoseconds, wide bandwidth (~60 GHz), but with slow reconfigurability time (> 13 μs).

Device configuration

Numerical results

Conclusions