A narrow-spectrum long-wavelength VCSEL using a fiber Bragg grating

Abstract

A 1.3-μm vertical-cavity surface-emitting laser (VCSEL) with a fiber Bragg grating (FBG) as an external cavity was developed. VCSELs emit light vertically from the semiconductor substrate. They have a circular output beam and therefore have a merit of easy coupling with optical fibers. Long-wavelength VCSELs in the 1.3 or 1.55-μm bands have recently been developed, which are suitable for long-distance telecommunication using single mode fibers. In this study, we coupled a 1310-nm VCSEL with an FBG as a wavelength-selective external cavity. The FBG was inscribed into a single mode fiber and the reflectivity was 47%. A rod lens was used for coupling of the VCSEL and a fiber. Grating temperature was varied for tuning of the Bragg wavelength. The spectral width without using an FBG was 85 pm FWHM, then the spectral width decreased to 64 pm FWHM by using an FBG at a temperature of 50°C. Further narrowing to 52 pm FWHM was obtained by an optimized diode current. It is expected that the wavelength dispersion in optical fiber transmission can be reduced by using an FBG.