Fiber Bragg gratings for laser interferometry with VCSEL diode at 760 nm wavelength

Abstract

Improvement of the linewidth and the mode-hop free tuning range of the Vertical Cavity Surface Emitting Laser (VCSEL) diode is the main goal of our upcoming Fiber Bragg Gratings (FBGs). The VCSEL with the fiber grating will be very suitable laser source for new generation of the absolute and the incremental laser interferometers based on our published VCSEL interferometer. The linewidth of the emission spectrum and the mode-hop free tuning range of the wavelength are critical in laser interferometry. The full width in half maximum (FWHM) linewidth of VCSEL at 760 nm wavelength is 100 MHz approximately. Tuning range up to 1 nm was measured by a highly precise commercial lambdameter with 0.1 pm resolution. To improve such a characteristic a high precise FBG must be selected. On the basis of our simulations and measurements of the commercially available fiber gratings we designed a special 100 mm long fiber Bragg grating with apodization. We expect the application of the FBG to improvement of the linewidth and mode-hop free tuning range of VCSEL at the wavelength 760 nm to increase resolution of laser interferometer based on VCSEL diode.