The output power and emission wavelengths of most of today's dense wavelength division multiplexing (DWDM) transmitters are highly sensitive to changes in temperature and injection current, requiring costly and complex compensation methods. Researchers at Huazhong University of Science and Technology in Wuhan, China, have proposed an alternative device for such transmissions using a stable semiconductor-optical-amplifier-based laser with cascaded sampled fiber gratings as a comb filter. In the May issue of IEEE Photonics Technology Letters, they reported that they have used such a device to produce five lasing lines from 1552 to 1555.5 nm with fixed spacings of 0.8 nm.