Ultralong continuously tunable parametric delays via a cascading discrete stage

Yitang Dai,Amy C Turner-Foster,Chris Xu,Yoshitomo Okawachi,Michal Lipson,Alexander L Gaeta

doi:10.1364/oe.18.000333

Abstract

We report experimental demonstration of an all-optical continuously tunable delay line based on parametric mixing with a total delay range of 7.34 mus. The bit-error rate performance of the delay line was characterized for a 10-Gb/s NRZ data channel. This result is enabled by cascading a discrete delay line that consists of 16 wavelength-dependent delays and a continuously tunable delay stage. Four wavelength conversion stages based on four-wave mixing in silicon waveguides were performed in order to achieve wavelength-preserving operation. The wavelength-optimized optical phase conjugation scheme employed in the delay line is capable of minimizing the residual dispersion for the entire tuning range.

Highlights

The ability to create precise all-optical delays, i.e., being able to control the arrival times of optical data streams on the physical level, is highly desirable in many areas such as communication networking [1], optical coherence tomography [2], optical control of phased array antennas for radio frequency communication [3], light detection and sensing [4], optical sampling [5], and pattern correlation [6]
Discrete optical delays, which can be generated by combining a series of fixed delay lines with different amounts of delay in parallel [7], are capable of a large range of discretely tunable delays with large granularity
A larger tunable delay range is usually achieved by the “wavelength conversion and dispersion” delay scheme, which takes advantage of the group-velocity dispersion (GVD) in an optical fiber for generating a wavelength-dependent optical delay [10,11,12,13,14,15,16,17,18,19,20]

Summary

Introduction

The ability to create precise all-optical delays, i.e., being able to control the arrival times of optical data streams on the physical level, is highly desirable in many areas such as communication networking [1], optical coherence tomography [2], optical control of phased array antennas for radio frequency communication [3], light detection and sensing [4], optical sampling [5], and pattern correlation [6]. A continuously tunable optical delay is required as the data rate increases since the time interval between adjacent bits is small. With dispersion management using the wavelength-optimized optical phase conjugation [17], delay ranges larger than 1 μs have been demonstrated experimentally without accumulating excessive residual GVD [17,18]. The increasing residual dispersion slope (which varies within the tuning range so that it cannot be fully compensated [17]) will impact the system performance, at high data rates. We experimentally demonstrate the first continuously tunable optical delay line with extended delay range via a cascading discrete stage. Using the wavelength-optimized optical phase conjugation scheme, zero residual GVD can be achieved throughout the tuning range. The bit-error-rate (BER) performance of the system is experimentally characterized using 10Gb/s NRZ data

System design and performance

Conclusion