A simple technique of ripple minimization for highly reflective fiber Bragg grating (FBG) is demonstrated by use of
natural gaussian beam shape. After writing FBG by interference beam pattern of gaussian shape, an equalization of
average refractive index is performed by means of post-exposure by non-interfering gaussian beam shifted in left and
right directions relative to FBG center at distance equal to beam radius.
Frequency doubling in a 4-mirror Z-type cavity with BBO crystal and a large-bore argon discharge tube has been simulated and tested experimentally. Power of the second harmonic as dependent of the position of focusing mirror and crystal, fundamental laser power is measured. The measured dependences satisfactory agree with the calculated ones. Cavity optimization results in achievement of ~1 W output power at 244 nm.
Uv system of high output power and large coherence length operating at 244 and 257nm is described. Single-frequency argon laser output is frequency-doubled by BBO crystal placed in external resonant cavity. Applications of the system for fiber grating fabrication are discussed. System for characterization of fiber gratings based on the optical spectrum analyzer is described. Technique of temperature tuning of FBGs forming a cavity of a fiber Raman laser is applied that provides high sensitivity of Raman laser output power and spectra to a temperature difference of the cavity FBGs. Possible applications of such scheme in fiber sensing are discussed.