Generation of UV-Vis correlated photon pairs using PP-LaBGeO₅

Area of Science:

• Nonlinear optics
• Quantum optics
• Materials science

Background:

• Periodically poled crystals are crucial for nonlinear optical processes like second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC).
• LBGO (Lithium Barium Germanate Oxide) is a nonlinear crystal material with potential for generating entangled photons.

Purpose of the Study:

• To characterize the SHG and SPDC performance of a periodically poled bulk LBGO crystal.
• To assess the potential of PP-LBGO as a source for entangled photon pairs tunable to specific wavelengths.

Main Methods:

• Measurements of second-harmonic generation (SHG) efficiency.
• Temporal characterization of spontaneous parametric down-conversion (SPDC) using a Hanbury-Brown-Twiss (HBT) interferometer.
• Spectral analysis of the PP-LBGO source using an EMCCD spectrometer.

Main Results:

• Measured SHG efficiency of (3.52 ± 0.04) × 10^-3 %/W.
• Achieved a maximum coincidence-to-accidental ratio (CAR) of 244 and a pair generation rate (PGR) of (1.45 ± 0.47) × 10⁶ pairs s^-1 mW^-1.
• Demonstrated a temperature-tunable spectrum of entangled photon pairs centered at 532 nm, with signal and idler photons tunable from 507 to 556 nm using a 2.10 µm poling period.

Conclusions:

• The PP-LBGO crystal is a viable source for generating tunable entangled photon pairs.
• This work supports the development of future wave-guided entangled-photon sources for ultraviolet (UV) applications.