New technology for fabricating multiple pitch gratings for WDM laser arrays

For high-capacity wavelength division multiplexing (WDM) optical communication systems, distributed feedback (DFB) laser arrays having a nanometer wavelength spacing are highly desirable. Most of the WDM laser arrays fabricated today used E-beam lithography to achieve accurate control of the channel spacing. However, E-beam lithography is not suitable for high volume production because of its low throughput and high cost. Recently, we developed a new fabricating process, cascaded self-induced holography, to form submicron gratings. This process is simple, reliable, and insensitive to vibrations and environmental changes. In this paper, we use cascaded self-induced holography to demonstrate multiple grating pitches having a period difference of a few angstroms between adjacent devices. This technique is particularly attractive for WDM laser arrays