Electronic Wavelength Tuning of Tunable Laser with Acousto-Optic Tunable Filter

We investigated the design of an acousto-optic tunable filter (AOTF) as a wavelength-tuning element of a tunable laser in terms of the dependences of the diffraction efficiency, bandwidth and stability of the wavelength on the internal temperature of the AOTF. In a simulation, the diffraction efficiency reached more than 90% in the wavelength region from 700 to 1000 nm, and the variation of diffraction efficiency was less than ±1.0% at temperatures from 20 to 30 °C in the AOTF. In an experiment, we demonstrated that the internal temperature of the AOTF induces a wavelength shift of 0.12 nm/°C. Most experimental results for the output characteristics of the tunable laser with the AOTF agreed with those predicted numerically.