We review the physical properties, linear and nonlinear optical characteristics, and phase‐matching configurations of BiB₃O₆ (BIBO), the first low‐symmetry (monoclinic) inorganic nonlinear crystal that has found broad applications for frequency conversion of laser sources from the UV, across the visible, to the near‐IR based on three‐wave interactions. We describe in detail the most relevant optical properties that make this material an attractive candidate for nonlinear frequency conversion of laser light in general, and ultrafast femtosecond laser sources in particular. With special focus on ultrafast frequency conversion, characteristics such as group‐velocity mismatch and spectral acceptance, parametric gain bandwidth, group‐velocity dispersion, as well as angular acceptance and spatial walk‐off are evaluated and optimum configurations for the attainment of maximum conversion efficiency, minimum pulse duration, and highest spatial beam quality are identified and compared with the most widely established alternative borate crystal, β‐BaB₂O₄. Experimental results are presented on both parametric up‐ and down‐conversion of femtosecond pulses, from the high‐energy, low‐repetition‐rate (1 kHz) to the low‐energy, high‐repetition‐rate (56–76 MHz) regime, demonstrating the unique versatility of BIBO for efficient frequency conversion of femtosecond pulses with broad tunability from 250 nm in the UV, throughout the visible, up to ∼ 3000 nm in the IR.

Bi₂ZnOB₂O₆ nonlinear optical single crystals were grown by means of the Kyropoulos method from stoichiometric melt. The second and third harmonic generation (SHG/THG) of Bi₂ZnOB₂O₆ crystals were investigated by the SHG/THG Maker fringes technique. Moreover, SHG microscopy studies were carried out providing two-dimensional SHG images as a function of the incident laser polarization. The high nonlinear optical efficiency combined with the possibility to grow high quality crystals make Bi₂ZnOB₂O₆ an excellent candidate for photonic applications.

Efficient generation of tunable femtosecond pulses in the blue is reported in the nonlinear crystal ${\mathrm{BiB}}_3{\mathrm{O}}_6$. By use of fundamental pulses from a mode-locked Ti:sapphire laser at 76 MHz, single-pass second-harmonic average powers of as much as 830 mW have been generated at 50% conversion efficiency, and a tunable range of 375–435 nm in the blue is demonstrated. Temporal measurements using cross correlation of the fundamental and second-harmonic pulses in a $100‐\mathit{\mu }\mathrm{m}$-thick $\beta ‐{\mathrm{BaB}}_2{\mathrm{O}}_4$ crystal result in blue pulse durations of 220 fs for 130-fs fundamental pulses. Direct experimental comparison with $\beta ‐{\mathrm{BaB}}_2{\mathrm{O}}_4$ confirms the superior performance ${\mathrm{BiB}}_3{\mathrm{O}}_6$ for second-harmonic generation of femtosecond pulses.

The authors report efficient third harmonic generation of microjoule picosecond pulses at $355\mathrm{nm}$ in the nonlinear optical material $\mathrm{Bi}{\mathrm{B}}_3{\mathrm{O}}_6$ . Using two crystals of $\mathrm{Bi}{\mathrm{B}}_3{\mathrm{O}}_6$ cut for type I $(e+e\to o)$ phase matching in optical $yz$ plane for second and third harmonic generation and fundamental pulses from a mode-locked, amplified picosecond Nd:YAG laser at $1.064\mu \mathrm{m}$ , they have achieved conversion efficiencies of as much as 50% at $355\mathrm{nm}$ . Third harmonic pulse energies of up to $216\mu \mathrm{J}$ in $29\mathrm{ps}$ pulses at $25\mathrm{Hz}$ repetition rate have been obtained for $35\mathrm{ps}$ fundamental pulses. They have also determined the magnitude of two-photon absorption coefficient in $\mathrm{Bi}{\mathrm{B}}_3{\mathrm{O}}_6$ at $355\mathrm{nm}$ to be 0.71 and $1.37\mathrm{cm}∕\mathrm{GW}$ for ordinary and extraordinary polarizations, respectively.