Practical considerations of using tunable lasers for packet routing in multiwavelength optical networks

Using tunable lasers for burst or packet routing in practical IP-centric networks faces many challenges. The wavelength accuracy and stability will affect the ways of encoding payload and headers. In particular, using subcarrier multiplexing to carry the header will make the wavelength stability of a tunable laser a very challenging problem. We investigate the effects of tuning hysteresis on the switching speed and channel control. Optimizing the device structure and lowering the bias current can reduce the hysteresis effect. Integration of tunable laser with semiconductor optical amplifiers can provide output gating during tuning and can allow for reducing the hysteresis. We demonstrate tunable lasers that can switch to accurate and stable DWDM wavelengths in 10 nanoseconds. We conclude that fast tunable lasers can be applied for optical burst or packets switching by improving the tuning control as well as optimizing the device structure.