Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

Abstract

A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power to 111 mW of 397.5 nm UV output. For LBO crystal, with 1.34 W of mode-matched 795 nm power, 770 mW of 397.5 nm UV output is achieved, implying a doubling efficiency of 57.4%. For BiBO crystal, with 323 mW of mode-matched 795 nm power, 116 mW of 397.5 nm UV output is achieved, leading to a doubling efficiency of 35.9%. The generated UV radiation has potential applications in the fields of quantum physics.

Frequency ratio of Yb and Sr clocks with 5 × 10−17 uncertainty at 150 seconds averaging time

“…A 798-nm diode laser is useful for constructing an external cavity laser, since the laser has good longitudinal and transverse modes and is widely available. Conventionally, a nonlinear optical crystal, e.g., a lithium triborate (LBO), a barium borate (BBO), a BiB 3 O 6 , or a periodically poled KTiOPO 4 crystal, has been placed in a power-buildup cavity to obtain a high SHG power [27][28][29][30][31][32][33][34]. The output power at 399 nm using this method is typically higher than that of the blue diode laser system.…”

The origin of irreversibility and thermalization in thermodynamic processes

“…A fraction of the total energy is converted and emitted as photons of double the excitation frequency. This is also a second-order process that requires high laser intensities for efficient conversion [141].…”

High power continuous laser at 461 nm based on a compact and high-efficiency frequency-doubling linear cavity

“…Periodically-poled crystals operating at quasi-phase matching condition have been dismissed, despite a promising high conversion efficiency (𝑑 eff ), because of their major limitations at high power induced by the photo-refractive beam distortion, the blue-induced infrared absorption [12], and thermal effects [13]. β-barium borate (BBO) [14] and bismuth triborate (BIBO) [15] crystals were discarded because of their large walk off angle (see Tab. 1).…”

“…Parameters ppsLT [13] ppKTP [18] BiBO [15] BBO [14] The LBO crystal is tightly fixed on the cavity axis; it has a length of 15 mm and a cross section of 3×3 mm 2 . The crystal is cut for normal incidence 𝜃 = 90 𝑜 , 𝜙 = 21 𝑜 at the phase matching at 48 𝑜 𝐶 and has a two layer antireflection coating working at 922 nm (reflectivity R<0.1%) and 461 nm (R<0.3%).…”