Single-pass Sum-frequency Generation Research Articles

Broadband and Triple-Wavelength Continuous Wave Orange Laser by Single-Pass Sum-Frequency Generation in Step-Chirped MgO:PPLN

We have demonstrated sum-frequency generation of a compact continuous-wave orange laser in a step-chirped magnesium oxide doped periodically poled lithium niobate in single-pass mode. A 974 nm laser diode was mixed with a C-band amplified spontaneous emission laser source to yield a triple-wavelength operation at 594.9, 596.9, and 598.6 nm with a maximum output power of 9.3 mW and broad bandwidth of ~4.4 nm. The triple-wavelength output power stability was ~2.5% in 30 min. This technique provides a path to generate broadband laser sources at shorter wavelengths which are potentially useful for biomedical and spectroscopic applications.

Multi-peak tunable CW orange laser based on single-pass sum frequency generation in step-chirped MgO: PPLN

We report an all-solid-state tunable CW orange laser based on single-pass sum-frequency generation in step-chirped PPMgO: LN crystal. Two laser sources, a tunable laser (1550 nm) and an ASE laser (1525–1650 nm) are used interchangeably as pumps and mixed with a fixed 975 nm signal laser. Up to 4.3 mW at 597 nm is generated corresponding to 0.87% nonlinear conversion efficiency and the beam quality (M2) value of about 2.5 is measured. The output wavelength can be tuned up to ~ 5.66 nm by varying the position of focusing inside the crystal and by temperature, which makes possible the practical application of our device for wavelength selection and diversity in the orange spectral range.

A Tunable CW Orange Laser Based on a Cascaded MgO:PPLN Single-Pass Sum-Frequency Generation Module

We report an all-solid-state continuous wave (CW) tunable orange laser based on cascaded single-pass sum-frequency generation with fundamental wavelengths at 1545.7 and 975.2 nm using two quasi-phase-matched (QPM) MgO-doped periodically poled lithium niobate (MgO:PPLN) crystals. Up to 10 mW of orange laser is generated in the cascaded module corresponding to a 10.4%/W nonlinear conversion efficiency. The orange output showed a temperature tuning rate of ~0.05 nm/°C, and the beam quality (M2) value of the orange laser was about 2.0. We use this technique to combine the high efficiency offered by uniformly poled crystals and the broad input wavelength acceptance characteristic of step-chirped structures.

Efficient single-pass third-harmonic generation from 1560 nm to 520 nm for pumping doubly-resonant OPO

A ~545 mW single-frequency tunable 520 nm green laser has been demonstrated using a periodically-poled potassium titanyl phosphate (PPKTP) bulk crystal based on single-pass third-harmonic generation (THG) of a 1560 nm laser via single-pass second-harmonic generation (SHG) followed by single-pass sum-frequency generation (SFG). In single-pass SHG, two cascaded periodically-poled magnesium-oxide-doped lithium niobate (PPMgO:LN) crystals were used, and ~3.5 W of 780.25 nm doubled laser output is produced, corresponding to maximum doubling efficiency of 26.8%. The system can provide a pump source (520 nm) for an optical parametric oscillator for two-colour entangled continuous-variable optical field generation at 1560 and 780 nm and two-colour local oscillators for homodyne detection.

Realization and characterization of single-frequency tunable 637.2 nm high-power laser

We report the preparation of narrow-linewidth 637.2nm laser device by single-pass sum-frequency generation (SFG) of two infrared lasers at 1560.5nm and 1076.9nm in PPMgO:LN crystal. Over 8.75W of single-frequency continuously tunable 637.2nm laser is realized, and corresponding optical-optical conversion efficiency is 38.0%. We study the behavior of crystals with different poling periods. The detailed experiments show that the output red lasers have very good power stability and beam quality. This high-performance 637.2nm laser is significant for the realization of high power ultra-violet (UV) 318.6nm laser via cavity-enhanced frequency doubling. Narrow-linewidth 318.6nm laser is important for Rydberg excitation of cesium atoms via single-photon transition.

Stable, high-power, Yb-fiber-based, picosecond ultraviolet generation at 355 nm using BiB_3O_6

We report a stable, high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 355 nm based on single-pass sum-frequency generation of a mode-locked Yb-fiber laser at 1064 nm in the nonlinear crystal BiB3O6. By performing single-pass second-harmonic generation (SHG) in a 30-mm-long LiB3O5 crystal, up to 9.1 W of average green power at 532 nm is obtained at a single-pass SHG efficiency of 54%. The generated green pulses have a duration of 16.2 ps at a repetition rate of 79.5 MHz, with a passive power stability better than 0.5% rms and a pointing stability <12 μrad over 1 h, in high beam quality. The green radiation is then sum-frequency-mixed with the fundamental in a 10-mm-long BiB3O6 crystal, providing as much as 1.2 W of average UV power, at an infrared-to-UV conversion efficiency of 7.2%, with a passive power stability better than 0.4% rms over 3 h and a pointing stability <45 μrad over 1 h, in TEM00 spatial profile.

Stable, continuous-wave, ytterbium-fiber-based single-pass ultraviolet source using BiB_3O_6

We report stable continuous-wave (CW) ultraviolet (UV) generation at 354.7 nm using single-pass sum-frequency-generation (SFG) of a CW Yb-fiber laser at 1064 nm in the nonlinear crystal, BiB3O6. The 532 nm radiation is obtained by single-pass second-harmonic generation of the Yb-fiber laser in a 30-mm-long MgO:sPPLT crystal. Using a 10-mm-long BiB3O6 crystal for SFG, with a measured angular acceptance bandwidth of 0.57 mrad, we generate as much as 68 mW of CW single-frequency UV radiation with a passive power stability better than 3.2% rms over 2 h and frequency stability better than 436 MHz over 2.5 h. The UV output beam has a TEM00 spatial profile with M(x)(2)<1.6 and M(y)(2)<1.8.

Single-frequency blue light generation by single-pass sum-frequency generation in a coupled ring cavity tapered laser

A generic approach for generation of tunable single frequency light is presented. 340 mW of near diffraction limited, single-frequency, and tunable blue light around 459 nm is generated by sum-frequency generation (SFG) between two tunable tapered diode lasers. One diode laser is operated in a ring cavity and another tapered diode laser is single-passed through a nonlinear crystal which is contained in the coupled ring cavity. Using this method, the single-pass conversion efficiency is more than 25%. In contrast to SFG in an external cavity, the system is entirely self-stabilized with no electronic locking.

Sodium temperature lidar based on injection seeded Nd:YAG pulse lasers using a sum-frequency generation technique

We report on a sodium (Na) temperature lidar based on two injection seeded Nd:YAG pulse lasers using single-pass sum-frequency generation. The laser power at 589 nm is 400 mW (40 mJ per pulse at a repetition rate of 10 Hz) and the pulse width is 22 nsec FWHM. The narrowband laser tuned to the Doppler broadened Na D2 spectrum enables us to measure the temperature of the mesopause region (80-115 km). This solid-state transportable system demonstrated high performance and capability at Syowa Station in Antarctica for 3 years and at Uji in Japan for an additional year without any major operational troubles.

A 7.5 W quasi-continuous-wave sodium D2 laser generated from single-pass sum-frequency generation in LBO crystal

We report a high-power, narrow linewidth and tunable quasi-continuous-wave (QCW) yellow laser system at 589.159 nm. The system is of a design employing single-pass sum-frequency generation (SFG) in a LBO crystal by mixing the 1064 nm with 1319 nm lines from a two diode-side-pumped Nd:YAG master oscillator-power amplifier (MOPA) laser system. With the pump power of 35 W at 1064 nm and 25 W at 1319 nm, a 7.5 W QCW output of the SFG yellow laser at 589.159 nm, which is the vacuum wavelength of a general sodium D2 line, is obtained with a linewidth less than 0.7 GHz and a beam-quality factor M 2=1.2. The wavelength of the laser can be precisely step-tuned from 589.148 to 589.167 nm with an increment of 0.13 pm by means of a temperature-controlled etalon.

Single-pass sum-frequency-generation of 589-nm yellow light based on dual-wavelength Nd:YAG laser with periodically-poled LiTaO_3 crystal

We demonstrate a compact all-solid-state yellow laser source based on Q-switched dual-wavelength Nd:YAG laser and periodically-poled LiTaO(3) crystal. 589-nm yellow light was generated by single-pass sum-frequency generation of the fundamental IR waves at 1064 and 1319 nm. The maximum output power of yellow light was 506 mW and the corresponding conversion efficiency was approximately 5.5% [W(-1)cm(-1)].

Simultaneously phase-matched parametric processes in a single-pass interaction for efficient visible generation

We demonstrate simultaneously phase-matched cascaded optical parametric amplification (OPA) and sum-frequency generation (SFG) processes in a single-pass interaction in a BBO crystal, where the seed pulse is produced through the self-induced superfluorescence generation. Tunable femtosecond pulses in the blue-green spectral range are produced through the single-pass SFG interaction with a maximum conversion efficiency of about 12%.

Continuous-wave sodium D_2 resonance radiation generated in single-pass sum-frequency generation with periodically poled lithium niobate

With two cw single-mode Nd:YAG lasers at 1064 and 1319 nm and a periodically poled lithium niobate crystal, 11 mW of 2 kHz/100 ms bandwidth single-mode tunable 589 nm cw radiation has been detected using single-pass sum-frequency generation. The demonstrated conversion efficiency is approximately 3.2%[W(-1) cm(-1)]. This compact solid-state light source has been used in a solid-state-dye laser hybrid sodium fluorescence lidar transmitter to measure temperatures and winds in the upper atmosphere (80-105 km); it is being implemented into the transmitter of a mobile all-solid-state sodium temperature and wind lidar under construction.

Sodium D_2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers

We report on a sodium D(2) resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.