Technical Insight
Monolithic arrays enable multi-wavelengths (research review)
The monolithic integration of DWDM sources is highly desirable for fabricating multi-wavelength transmitters. In work described at the International Semiconductor Laser Conference (ISLC 2000, p79), San-Liang Lee et al. from the National Taiwan University of Science and Technology demonstrated a novel technique for fabricating monolithic laser arrays of InGaAsP/ InP materials which can be used to obtain multiple wavelengths from a single wafer. The arrays dispense with grating fabrication techniques such as e-beam writing or selective area growth, and are formed from sampled grating DBR (SGDBR) lasers whose sampling periods vary from laser to laser. Uniformly-spaced DWDM wavelengths can then be generated without tuning if the two sides of the SGDBR mirrors are fabricated on waveguides of slightly different thickness. Laser arrays with channel spacings of 100 and 50 GHz were demonstrated with better than 40 dB SMSR and no mode hopping.
