BER performance in wavelength packet-switched WDM systems during nano-second wavelength switching events

Abstract

An important characteristic of wavelength tuneable laser transmitters is that as they tune between output wavelength channels they may generate light at a range of other wavelengths. This effect may ultimately influence the design of WDM wavelength packetswitched networks employing wavelength tuneable transmitters. We have investigated this effect by examining the BER transmission performance of a WDM channel as a function of the degree of attenuation of another WDM wavelength signal during fast wavelength switching events. Our results show the importance of attenuating the output signal from the wavelength switched laser in order to prevent performance degradations on the monitored data channel.

Cross-channel interference due to wavelength switching events in wavelength packed switched WDM networks

“…However, one of the difficulties in employing this type of laser in a WDM system is that when the laser is tuned between wavelengths it can generate spurious components [9]; these in turn would interfere with other channels in use. In previous work [10], we presented the characterisation of cross-channel interference from a single TL that was switched between two wavelengths. The spurious components generated during the switching event placed an error floor on the BER of a channel transmitted at the same wavelength as the spurious components.…”

“…Depending on the particular channel transition the time taken to be within +/-15 GHz of the final frequency is typically in the order of 20-50 ns, during this 20-50 ns period spurious output wavelength may be generated by the TL. The main difference in comparison to the TL module used in [10] is a Semiconductor Optical Amplifier (SOA) placed at the output of the tunable laser. The SOA can be turned off to blank the laser output for a period of 50 ns starting from the moment the laser tuning (to a different wavelength) is initialised.…”

Nanosecond Channel-Switching Exact Optical Frequency Synthesizer Using an Optical Injection Phase-Locked Loop (OIPLL)

“…The switching times of fiber-based etalon stabilisers are restricted to millisecond timescales (2 ms) [5], not compatible with the requirements of optical packet-and burst-switched networks operating on the microsecond to nanosecond timescale. Recently, locked widely tuneable lasers have reached switching speeds of 50 ns (channel spacing of 100 GHz), with a frequency error 8 GHz [6].…”