We investigate the use of different direct detection modulation formats in a wavelength switched optical network. We find the minimum time it takes a tunable sampled grating distributed Bragg reflector laser to recover after switching from one wavelength channel to another for different modulation formats. The recovery time is investigated utilizing a field programmable gate array which operates as a time resolved bit error rate detector. The detector offers 93 ps resolution operating at 10.7 Gb/s and allows for all the data received to contribute to the measurement, allowing low bit error rates to be measured at high speed. The recovery times for 10.7 Gb/s non-return-to-zero on–off keyed modulation, 10.7 Gb/s differentially phase shift keyed signal and 21.4 Gb/s differentially quadrature phase shift keyed formats can be as low as 4 ns, 7 ns and 40 ns, respectively. The time resolved phase noise associated with laser settling is simultaneously measured for 21.4 Gb/s differentially quadrature phase shift keyed data and it shows that the phase noise coupled with frequency error is the primary limitation on transmitting immediately after a laser switching event.
© 2012 OSA
Enabling Optical Devices for Scalable Networks
Original Manuscript: February 29, 2012
Revised Manuscript: July 1, 2012
Manuscript Accepted: July 27, 2012
Published: August 24, 2012
John A. O’Dowd, Kai Shi, Anthony J. Walsh, Vivian M. Bessler, Frank Smyth, Tam N. Huynh, Liam P. Barry, and Andrew D. Ellis, "Time Resolved Bit Error Rate Analysis of a Fast Switching Tunable Laser for Use in Optically Switched Networks," J. Opt. Commun. Netw. 4, A77-A81 (2012)