LBO (Lithium Triborate, LiB3O5) crystal is recognized as one of the most exceptional non-linear crystals, particularly esteemed for its role in noncritical phase-matched laser frequency doubling. This crystal stands out in the ultraviolet spectrum, having been effectively utilized in the second and third harmonic generation of YLF, YAG, and YAP lasers.

The LBO crystal is characterized by its broad transmission band and excellent ultraviolet transmittance, paired with slightly deliquescent properties. Its superior physical and chemical stability, combined with a moderate non-linear optical coefficient and high optical uniformity, make it a preferred choice for various optical applications. Moreover, it boasts a high damage threshold, a large allowable angle, and a minimal walk-off angle, which collectively contribute to its widespread use in high-average power harmonic generation and parametric oscillation fields.

The standout feature of the LBO crystal is its ability to utilize temperature tuning for achieving non-critical phase matching (NCPM). In this configuration, the walk-off angle between the fundamental frequency light and the second harmonic is zero, theoretically allowing the effective length of the LBO crystal to extend to infinity. This property compensates for its relatively small non-linear coefficient. The crystal's substantial damage threshold enables high-power fundamental wave pumping, significantly enhancing the conversion efficiency of fundamental frequency light in extra-cavity frequency doubling of pulsed lasers. This results in markedly improved beam quality and frequency light stability.

Overall, the LBO crystal's unique properties and advantages make it an invaluable component in the field of laser technology, particularly for applications requiring high precision and efficiency in frequency conversion processes.