Nanosecond Optical Parametric Generator Research Articles

Enhanced two-photon excited fluorescence by ultrafast intensity fluctuations from an optical parametric generator

We evaluate the enhancement of two-photon excited fluorescence from fluorescent dye by ultrafast intensity fluctuations of light generated by a nanosecond optical parametric generator (OPG). By modifying the well-established techniques for measuring the second-order coherence on ultrashort timescale, we observed the enhancement of the fluorescence from Rhodamine B dye by a factor of two due to the bunching effect of light. A nanosecond OPG can be built at a much lower cost than the ultrashort pulse used in two-photon excitation microscopes. Therefore, our work paves the way toward a low-cost and efficient nonlinear microscope.

Efficient Nanosecond Dual-Signal Optical Parametric Generatorwith a Periodically Phase Reversed PPMgLN

We report an efficient nanosecond optical parametric generator (OPG)with a periodically-phase-reversed periodically poledMgO:LiNbO3(ppr-PPMgLN), which produces two pairs of signal andidler waves. The OPG is pumped by a 1.064 μm Q-switched Nd:YVO4laser. When the repetition rate is set at 10 kHz, the maximum averagetotal output power of 570 mW is achieved, including 410 mW ofdual-signal radiations and 160 mW of dual-idler radiations. The totalconversion efficiency is 32.5%. The tunable dual-signal wavelengths inthe range of 1.474–1.518 μm and 1.490–1.539 μm and thedual-idler of 3.826–3.558 μm and 3.726–3.451 μm are obtainedby changing the crystal temperature from 30°C to 200°C.

High power output quasi-continuous-wave nanosecond optical parametric generator based on periodically poled lithium niobate

We report on a high power output quasi-continuous-wave nanosecond optical parametric generator (OPG) of congruent periodically poled lithium niobate (PPLN) pumped by a 1064 nm acousto-opticallyQ-switched Nd: YVO4 laser (duration: 70 ns, repetition rate: 45 kHz, spatial beam qualityM2< 1.3). The OPG consists of a 38.7 mm long PPLN crystal with a domain period of 28.93 μ. With 5.43 W of average pump power the maximum average output power is 991 mW at 1517.1 nm signal wave of the PPLN OPG.

High-Average-Power Nanosecond Quasi-Phase-Matched Single-Pass Optical Parametric Generator in Periodically Poled Lithium Niobate

A pulsed nanosecond optical parametric generator (OPG) in periodicallypoled lithium niobate (PPLN) crystal is presented. The pump laser is anacousto-optically Q-switched Nd:YVO4 laser with themaximum average power of 6.58 W. When the repetition rate is 50 kHz andthe pulse width of the pump source is 80 ns, the maximum average totaloutput power of the single-pass PPLN OPG is about 1.9 W, which includes1.322 W of 1.536 μm signal radiation. The length of the PPLNcrystal is only 38.7 mm (at room temperature) with a grating period of28.93 μm (at room temperature). The 1.502–1.536 μm signalradiation and 3.652–3.465 μm idler radiation are obtained byadjusting the PPLN crystal temperature from 155 degrees C to 250 degrees C.

Widely tunable narrow-linewidth nanosecond optical parametric generator with self-injection seeding

This paper reports a widely tunable narrow-linewidth nanosecond optical parametric generator (OPG) with a pulse-repetition rate of 10 kHz. The OPG consists of a 55-mm-long periodically poled lithium niobate crystal with a domain period of 29.5 μm. At an average pump power of 2.0 W the OPG emitted 0.33 W of signal power and 0.17 W of idler power. The wavelength and spectral width of the OPG are controlled by self-injection seeding. For this purpose, a small fraction of the OPG’s pulsed signal radiation is used as seed radiation for the next OPG pulse. In order to overlap in time the seed pulse with the succeeding pump pulse, the seed pulse is delayed by a 22-km-long single-mode fiber. For narrowing the spectrum of the seeded OPG output, the seed radiation is spectrally filtered by a tunable fiber Fabry–Perot interferometer (FFPI). The OPG signal radiation could be tuned from 1547 to 1605 nm by changing the OPG’s crystal temperature and by tuning simultaneously the FFPI. The corresponding idler wave tuned from 3157 to 3413 nm. Within the whole tuning range, the linewidth of the signal wave was less than 185 MHz. Compared to the 240-GHz linewidth of the free-running OPG, the linewidth of the seeded OPG is thus narrowed by more than three orders of magnitude. By tuning the FFPI, continuous wavelength tuning has been demonstrated within the gain spectrum of the OPG over a range of 820 GHz.

Pulsed nanosecond optical parametric generator based on periodically poled lithium niobate

Abstract In this paper we report on a pulsed nanosecond optical parametric generator (OPG) of congruent periodically poled lithium niobate (PPLN). The OPG is excited by TEM 00 single frequency pulses (duration: 10 ns, repetition rate: 10 kHz) of a Q-switched Nd:YVO 4 laser system. With 7.2 W of average power the OPG generated 1.6 W of signal and 0.76 W of idler radiation. The signal and idler waves are tunable in the range of 1.56–1.64 and 3.34–3.03 μm, respectively, by changing the temperature of the PPLN crystal. Injection seeding with 3 mW of cw 1.580 μm light of a tunable DFB diode laser narrowed the spectral width of the OPG signal wave to less than 140 MHz.

Pulse-to-pulse wavelength tuning of an injection seeded nanosecond optical parametric generator with 10 kHz repetition rate

This paper reports on the pulse-to-pulse wavelength tuning of a multiwatt narrow-linewidth nanosecond optical parametric generator (OPG). The OPG consists of a 55 mm long periodically poled lithium niobate (PPLN) crystal with a domain period of 29.75 μm. Excited by 5.7 W of 1064 nm laser pulses (duration: 10 ns, repetition rate: 10 kHz, spatial beam quality M2=1.2) the OPG generates 1.78 W of signal radiation and 0.79 W of idler radiation. The total output of 2.57 W corresponds to a crystal internal efficiency of 64%. The wavelength and spectral width of the OPG is controlled by injecting the cw single mode radiation of a 1580.2 nm DFB diode laser. A seed power as low as 20 μW is sufficient for complete control of the wavelength and the (90 MHz) linewidth of the OPG output. Fast tuning of the diode laser frequency is possible with a rate of up to 6×107 GHz/s by changing the diode current. This allows pulse-to-pulse wavelength tuning of the 10 kHz OPG over a range of 25 GHz limited only by the maximum variation of the current (of 60 mA) allowed for the DFB diode laser used. Increasing the current from 35 mA to 95 mA changed the diode power from 0.3 mW to 5.7 mW. Since these power levels are well above the required minimum seed power, the change of the diode current changes the wavelength of the OPG, but not its linewidth or its output power.

Nanosecond periodically poled lithium niobate optical parametric generator pumped at 532 nm by a single-frequency passively Q-switched Nd:YAG laser

We report an efficient, visible, nanosecond optical parametric generator of periodically poled lithium niobate pumped at 532 nm by a frequency-doubled, diode-pumped, passively Q -switched, single-mode Nd:YAG laser with 90-muJ pulse energy. The signal radiation is tunable from 637 to 593 nm. The maximum signal-conversion efficiency is 23%. Optical parametric amplification of a He-Ne laser at 632.8 nm is also studied.