Multi-order, automatic dispersion compensation for 1.28 Terabaud signals Yvan Paquot a , Jochen Schr¨oder a , J¨ urgen Van Erps a,b , Trung D. Vo a , Mark D. Pelusi a , Steve Madden c , Barry Luther-Davies c and Benjamin J. Eggleton a a Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Science (IPOS), School of Physics A28, University of Sydney, NSW 2006, Australia; b Vrije Universiteit Brussel, Brussels Photonics Team, Dept. of Applied Physics and Photonics, Pleinlaan 2, 1050 Brussel, Belgium; c CUDOS, Laser Physics Centre, Australian National Univ., Canberra, A.C.T. 0200, Australia ABSTRACT Transmitting ultra-high symbol rate optical signals remains a challenge due to their high sensitivity to fluctu- ations of GVD and higher orders of dispersion in the transmission link. Being able to cancel the impairments due to those fluctuations is a key requirement to make transmission of ultrashort optical pulses practical. We demonstrate an automatic compensation scheme able to keep an Optical Time Division Multiplexed (OTDM) signal stable at a bandwidth of up to 1.28 Tbaud in spite of external perturbations. Our approach is based on monitoring the signal with a photonic-chip-based all-optical RF-spectrum analyzer. The measurement of a single parameter extracted from the RF-spectrum is used to drive a multidimensional optimization algorithm. We apply the method to the real time simultaneous compensation for 2 nd ,3 rd and 4 th order dispersion using an LCOS spectral pulse shaper (SPS) as a tunable dispersion compensator. Keywords: Fiber optics communications, Optical Time Division Multiplexing, Dispersion compensation, Higher-order dispersion, All-optical RF-spectrum analyzer. 1. INTRODUCTION A promising approach for increasing the data capacity of optical fibers is ultra-high symbol rate signals created by Optical Time Division Multiplexing (OTDM) of low bit-rate signals. This technique allows symbol-rates (baudrate) above 1 Tbaud as shown in 1 and. 2 However, these high bandwidth signals are increasingly suscep- tible to impairments. Not only GVD, but also higher-orders of dispersion significantly affect the transmission, 3 making a dispersion compensation solution crucial for allowing practical use of OTDM. Techniques have been developed to monitor the signal quality 4 with terahertz bandwidth, allowing to detect impairments at such high baudrate. At Tbaud rates, the present dispersion compensation method (GVD cancellation by spans of Dispersion Compensating Fiber) is no longer sufficient as higher orders of dispersion must be taken into account and even slight drifts of the dispersion coefficients can be detrimental. Such fluctuactions can be due for example to temperature variations 5 . 6 Previous experiments have demonstrated solutions to higher orders of disper- sion and fluctuations, employing elaborate compensation schemes using concatenated specialty fibers, 7 phase modulators, 8 tunable fiber Bragg gratings 91011 , MEMS, 12 a spatial light modulator with a virtually imaged phase array 13 or parametric wavelength conversion. 14 However, these schemes were not able to handle simul- taneously multi-order dispersion and time variations, or did not include a dispersion measurement system. The signal was encoded using on-off keying (OOK) on a pulse train with 300 fs pulsewidth. This work shows that second, third and fourth orders of dispersion (β 2 , β 3 and β 4 ) can be compensated automatically and si- multaneously for a 1.28 Tb/s single channel OTDM signal. In our setup, a single parameter is extracted from Further author information: Send correspondence to Yvan Paquot (E-mail: yvan@physics.usyd.edu.au). Best Student Paper Award Nonlinear Optics and Applications VI, edited by Benjamin J. Eggleton, Alexander L Gaeta, Neil G. Broderick, Proc. of SPIE Vol. 8434, 84340I · © 2012 SPIE · CCC code: 0277-786X/12/$18 · doi: 10.1117/12.923031 Proc. of SPIE Vol. 8434 84340I-1 Downloaded from SPIE Digital Library on 15 May 2012 to 134.184.206.132. Terms of Use: http://spiedl.org/terms