Reflective Volume Bragg Grating with Transverse Chirp

Reflective uniform volume Bragg gratings are used as narrow-band output couplers in high-power lasers with different gain media. VBGs with a longitudinally chirped grating period are used for stretching and compression of short laser pulses in chirped pulse amplification schemes. Here we study transversely chirped volume Bragg gratings (TCVBGs) with uniform refractive index modulation along the longitudinal direction of reflection at any particular transverse point of incidence. While modeling of laser cavity utilizing TCVBG involves many different parameters not directly related to parameters of TCVBG, e.g. size of the pump beam, here we analyze the performance of TCVBG itself as a narrow-band filter in terms of Gaussian beam reflection. A wide range of resonant wavelength tunability based on a large value of the transverse chirp rate is preferred for many applications. On the other hand, in case of large chirp rate, a Gaussian beam experiences significantly different amplitude reflection coefficients over its aperture. That leads to reflectivity reduction and beam quality deterioration. We have analyzed the effect of transverse chirp rate on reflection efficiency and reflected beam quality depending on Gaussian beam size.