Transmission volume phase holographic gratings in photo-thermo-refractive glass written with femtosecond laser Bessel beams

Zhang Y. J. (1) , Zhang G. D. (2) , Chen C. L. (1) , Razvan Stoian (3) , Guanghua Cheng (2)

1 Shaanxi Key Laboratory for Condensed Matter Structure and Properties
2 Xi’an Institute of Optics and Precision Mechanics
3 LHC - Laboratoire Hubert Curien

Transmission volume phase holographic gratings were fabricated in bulk photo- thermo-refractive glass using zero-order femtosecond laser Bessel beams and subsequent thermal treatment. Microstructures composed of nano-sized crystals were observed in the exposed regions. The concentration of nano-crystals depended on the writing power, but the size of the nano-crystals was found to be quasi power-independent. Low writing power led to sparse nano-crystals, while optimized writing po wer achieved dense nano-crystals distribution and high refractive index change. Effects of the gratings thickness, writing laser power and thermal treatment on the diffraction efficiency were investigated. A maximum diffraction efficiency of 94.73% was achieved (at 532 nm testing wavelength) with 1 mm grating thickness at period of 5 μm

Keywords: laser fabrication

Domains: Optics / Photonic

Zhang Y. J., Zhang G. D., Chen C. L., Razvan Stoian, Guanghua Cheng. Transmission volume phase holographic gratings in photo-thermo-refractive glass written with femtosecond laser Bessel beams . Optical Materials Express, 2016, 6 (11), pp.3491. ⟨10.1364/OME.6.003491⟩. ⟨ujm-01432521⟩