β-BaB2O4 deep UV monolithic walk-off compensating tandem

Abstract

The generation of watt-level cw narrow-linewidth sources at specific deep UV wavelengths corresponding to atomic cooling transitions usually employs external cavityenhanced second-harmonic generation (SHG) of moderate-power visible lasers in birefringent materials. In this work, we investigate a novel approach to cw deep-UV generation by employing the low-loss BBO in a monolithic walkoff-compensating structure [Zondy et al, 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 L c = 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 = 570.4nm 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 ∼ −1nm 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.

Breaking the Inherent Interarrangement of [B3O6] Clusters for Nonlinear Optics with Orbital Hybridization Enhancement

“…The real sources of SHG effect and birefringence in Ca 2 B 3 O 6 X are analyzed by using the real-space atom-cutting method (Table ). Clearly, this series has similar theoretical results, in which both SHG and birefringence are significantly lost when [B 3 O 6 ] units are removed, while cations and halogens have little effect on the SHG and birefringence. Therefore, [B 3 O 6 ] primitives play an indispensable role in the Ca 2 B 3 O 6 X series of the SHG response and birefringence.…”

“…However for nonlinear optical (NLO) crystals, the ideal standard for the birefringence is “moderate” to avoid nonphase matching (too small) behavior and walk-off effects (too large). Like, the most representative for 0D e- [B 3 O 6 ] borates, β-BaB 2 O 4 crystal with a large birefringence of 0.12@ 1064 nm suffers from the large walk-off angles that limit the nonlinear interaction length. − With this, our preliminary review-type paper raises an interesting question: why are all of the [B 3 O 6 ] units in the borates with only such isolated units aligned in a coplanar arrangement? Since that moment, we have focused on how to regulate the arrangement of [B 3 O 6 ] units to achieve moderate birefringence in borate-based NLO crystals.…”

Drive laser system for the DC-SRF photoinjector at Peking University

“…For FHG using BBO crystal, the large walk-off angle [8] caused by BBO crystal's large birefringence limits the conversion efficiency and makes the transverse profile of UV laser beam far from Gaussian distribution. This problem can be solved by using a walk-off compensation system, where two or more crystals having the same cut and length [9][10][11] are arranged with the crystal optic axes in alternating directions (see Fig. 5).…”

Electronic structure of a potential optical crystal YBa3B9O18: Experiment and theory

“…1 The strong anisotropy makes the birefringence of this series of crystals to be about 0.12, which is comparable to that of the ␤-BaB 2 O 4 crystal, 2 making them especially promising in a number of optical applications such as liquid crystal displays, light modulators, color filters, wave plates, and optical axis gratings. 1 The strong anisotropy makes the birefringence of this series of crystals to be about 0.12, which is comparable to that of the ␤-BaB 2 O 4 crystal, 2 making them especially promising in a number of optical applications such as liquid crystal displays, light modulators, color filters, wave plates, and optical axis gratings.…”