Takuya NAYUKI,¹ Takashi FUJII,^1,* Koshichi NEMOTO,¹ Mikio KOZUMA,² Motonobu KOUROGI² and Motoichi OHTSU²

¹Electrical Physics Department, Komae Research Laboratory, Central Research Institute of Electric Power Industry, 11-1, Iwado Kita 2-chome, Komae, Tokyo, 201-8511 Japan ²Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8502 Japan

(Received June 5, 1998; Accepted July 3, 1998)

We developed a simple method of continuous wavelength sweep using a commercial laser diode (LD) without antireflection (AR) coating. A 630 nm AlGaInP LD was installed in a Littrow-type external cavity. In this cavity, the LD has the same effect as an etalon, and its free spectral range can be controlled easily by the LD drive current. By scanning the grating angle of the external cavity and LD drive current simultaneously, we obtained single-mode oscillation and continuous wavelength sweep of over 22 GHz without mode hopping. This technique is simple and inexpensive because it does not need AR coating on its output facet, and does not use a servo system which requires apparatuses such as a lock-in amplifier and local oscillator.

Key words : laser diode, external cavity, wavelength tuning, short wavelength, antireflection coating

* fujii@criepi.denken.or.jp