The effect of stitching errors on the spectral characteristics of DFB lasers fabricated using electron beam lithography

• Published in: Journal of lightwave technology Vol. 10; no. 9; pp. 1256 - 1266
• Main Authors: Kjellberg, T., Schatz, R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-09-1992; Institute of Electrical and Electronics Engineers
• Subjects: Distributed feedback devices; Electron beams; Exact sciences and technology; Fault tolerance; Fundamental areas of phenomenology (including applications); Gratings; Laser feedback; Laser modes; Lasers; Lithography; Optics; Physics; Semiconductor lasers; laser diodes; Stochastic processes; Stochastic systems; Writing; Spectral data; Single mode laser; Computer simulation; Electron beam lithography; Distributed feedback laser; Error; Semiconductor laser; high-resolution electron beam exposure; single-mode characteristics; simulation; indium compounds; Bragg grating; DFB lasers; fault tolerant laser design; gain margin; systematic errors; distributed feedback lasers; stochastic errors; laser gratings; gallium arsenide; gallium compounds; phase shifted lasers; electron beam lithography; diffraction gratings; high-speed writing; spectral characteristics; stitching errors; optical workshop techniques; semiconductor lasers; InP-InGaAsP laser; errors; III-V semiconductors
• ISSN: 0733-8724; 1558-2213; 1558-2213
• DOI: 10.1109/50.156877

Field stitching errors and their effect on the single-mode characteristics of distributed feedback (DFB) lasers fabricated using electron beam lithography were investigated. The stitching errors are associated with small-area, high-resolution electron beam exposure, which has the potential advantage of high-speed writing of laser gratings. Measurements show that the errors are composed of a systematic and a stochastic part. Their effect on the gain margin was simulated both for lambda /4 phase-shifted and optimized multiple-phase-shifted DFB lasers. Simulations show that the lasers are insensitive to the systematic part of the stitching errors if the number of errors is large enough. The stochastic part was found to give rise to a variation in gain margin of the DFB lasers. It is concluded that the field stitching accuracy in the high-resolution mode of a commercial system for electron beam lithography is sufficient to provide a high yield of single-mode lasers. However, it is essential that certain precautions be taken considering exposure conditions and that a fault tolerant laser design be used.< >