β-BaB2O4 deep UV monolithic walk-off compensating tandem

J. Friebe, K. Moldenhauer, E. M. Rasel, W. Ertmer, L. Isaenko, A. Yelisseyev, J. J. Zondy

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The generation of watt-level cw narrow-linewidth sources at specific deep-UV wavelengths corresponding to atomic cooling transitions usually employs external cavity-enhanced second-harmonic generation (SHG) of moderate-power visible lasers in birefringent materials. Among the oxo-borate materials, barium borate (β-BaB2O4 or BBO) combines the highest UV band edge and largest nonlinearity but suffers from large walk-off angles that limits the nonlinear interaction length. Alternative quasi-phase-matched (QPM) ferroelectrics are hardly suited for cavity-enhanced operation due to their much larger UV absorption and associated photo-refractive and thermal lensing effects, in addition to the difficult fabrication of fine-pitch domain gratings for short UV coherence lengths. In this work, we investigate an alternative approach to cw deep-UV generation by employing the low-loss BBO in a monolithic walk-off compensating structure [J.-J. Zondy, Ch. Bonnin, D. Lupinski, J. Opt. Soc. Am. B 20 (2003) 1675] to simultaneously enhance the effective nonlinear coefficient while minimizing the UV beam ellipticity under tight focusing. As a preliminary step to cavity-enhanced operation, and in order to apprehend the design difficulties stemming from the extremely low acceptance angle of BBO, we investigate and analyze the single-pass performance of a Lc = 8 mm monolithic walk-off compensating structure made of 2 optically-contacted BBO plates cut for type-I critically phase-matched SHG of a cw λ = 570.4 nm dye laser. As compared with a bulk crystal of identical length, a sharp UV efficiency enhancement factor of 1.65 has been evidenced with the tandem structure, but at ∼-1 nm from the targeted fundamental wavelength, highlighting the sensitivity of this technique when applied to a highly birefringent material such as BBO. Solutions to angle cut residual errors are identified so as to match accurately more complex periodic-tandem structure performance to any target UV wavelength, opening the prospect for high-power, good beam quality deep-UV cw laser sources for atom cooling and trapping.

Original languageEnglish
Pages (from-to)300-309
Number of pages10
JournalOptics Communications
Volume261
Issue number2
DOIs
Publication statusPublished - May 15 2006
Externally publishedYes

Keywords

  • Type-I monolithic walk-off compensation
  • UV atom cooling and trapping
  • UV cw second-harmonic generation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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    Friebe, J., Moldenhauer, K., Rasel, E. M., Ertmer, W., Isaenko, L., Yelisseyev, A., & Zondy, J. J. (2006). β-BaB2O4 deep UV monolithic walk-off compensating tandem. Optics Communications, 261(2), 300-309. https://doi.org/10.1016/j.optcom.2005.12.008