FOCUSED ION-BEAM LITHOGRAPHY OF MULTIPERIOD GRATINGS FOR A WAVELENGTH-DIVISION-MULTIPLEXED TRANSMITTER LASER ARRAY

Wavelength-division multiplexing with closely spaced multiple waveleng ths is of great interest for high-capacity data transmission. One majo r acid very critical requirement of such a system is the fabrication o f a laser array with very small wavelength separations (similar to 2 n m). In this paper, the design, fabrication, and performance of an inte grated eight-channel system is described. Focused ion beam lithography , with the beam deflection sensitivity modified from its calibrated va lue, is used to write the critical stepped-period distributed-Bragg-re flector gratings required to provide the tightly controlled multiple l aser frequencies. The outputs of the lasers are combined via curved wa veguides into a single optical output.