Phase-coherent optical frequency division by 3 of 532-nm laser light with a continuous-wave optical parametric oscillator

Phase-locked 3:1 division of an optical frequency was achieved with a continuous-wave monolithic optical parametric oscillator (OPO) pumped by a 532-nm Nd:YAG laser, by use of 5% MgO-doped LiNbO(3) as a nonlinear optical crystal. The OPO generated signal light (798 nm) with 4-mW power and idler light (1596 nm) with 3-mW power for a pump power of 68 mW. Approximately 2microW of second harmonics (SH's) of the idler light was produced by external-cavity-enhanced SH generation by use of a periodically poled LiNbO(3) crystal. The beat signal between the signal light and the SH of the idler light was observed with a signal-to-noise ratio of 40 dB at a 10-kHz bandwidth and was successfully phase locked to a signal from a synthesizer through the electro-optic effect of the crystal.     

Generation of all-solid-state, high-power continuous-wave 213-nm light based on sum-frequency mixing in CsLiB6O10

Achievement of more than 100 mW of pure continuous-wave deep-ultraviolet radiation at 213 nm has been demonstrated in an efficient all-solid-state laser system that uses two Brewster-cut CsLiB6O10 (CLBO) crystals. The first crystal is used for 266-nm generation by external resonant doubling of 532-nm radiation from a frequency-doubled Nd:YVO4 laser. Subsequent sum-frequency mixing is performed in a second CLBO crystal placed in a diode-pumped Nd:YAG laser cavity to mix the single-pass 266-nm output with circulating 1064-nm light.     

2.5-W, continuous-wave, 629-nm solid-state laser source

We report an efficient, high-power, cw, 629-nm laser source based on a diode-pumped Nd:YAG laser and a periodically poled lithium niobate (PPLN) frequency converter. This device integrates two separate frequency-conversion steps in a single crystal, taking advantage of the ability to fabricate PPLN with nearly arbitrary grating periods and phase-matching temperatures. This device uses a single PPLN crystal that has two grating regions in series. The first region quasi-phase matches a standard optical parametric oscillator process (1064nm?1540nm +3450nm), and the second region quasi-phase matches a sum-frequency process whereby the pump and the signal light make red light (1064nm+1540nm ?629nm). Using a four-mirror ring cavity, we were able to convert 21% of the 1064-nm pump to 629-nm output, yielding 2.5W of red output with 11.8W of input.     

Vapor-transport equilibrated near-stoichiometric lithium tantalate for frequency-conversion applications

Near-stoichiometric lithium tantalate (SLT) crystals were produced from congruent lithium tantalate by a vapor-transport equilibration process. Because of the resultant increase in photoconductivity and reduction in photogalvanism, the crystals showed no observable photorefractive damage at 514.5 nm up to the highest intensity used, 2 MW/cm2. The crystals also exhibited low green-induced infrared absorption, a Curie temperature of 693 degrees C, and a coercive field of 80 V/mm. The SLT samples were periodically poled with an 8-microm-period grating, permitting first-order quasi-phase-matched second-harmonic generation of 532-nm radiation at 43 degrees C. A 17-mm-long sample generated 1.6 W of continuous-wave output power at 532 nm for 50 h. With 150-ns pulses at a 100-kHz repetition rate in the same sample, 5-W average-power, 532-nm radiation was generated for 1000 h. No damage to the crystal and no aging effects were observed during these experiments.     

Distributed-feedback optical parametric oscillation by use of a photorefractive grating in periodically poled lithium niobate

We report a demonstration of distributed-feedback (DFB) optical parametric oscillation (OPO) by writing photorefractive gratings in periodically poled lithium niobate (PPLN). The photorefractive DFB structures were fabricated by illumination of PPLN with UV light through a photomask and by writing of PPLN with UV-light gated interfering laser beams at 532 nm. Evidence of OPO was observed from the spectral narrowing at the 1438.8- and the 619.3-nm signal wavelengths from 1064- and 532-nm-pumped PPLN crystals with the DFB grating periods phase matched to the 4084.5- and 3774-nm idler wavelengths, respectively.     

Single-frequency continuous-wave radiation from 0.77 to 1.73 microm generated by a green-pumped optical parametric oscillator with periodically poled LiTaO3

We describe a cw optical parametric oscillator (OPO) with multigrating periodically poled LiTaO(3) . Pumped by a single-frequency 532-nm laser, the OPO emits single-frequency radiation at wavelengths from 0.77 to 1.73mum with as much as 60 mW of output power. Mode-hop-free operation for as long as 50 min, a low frequency drift (<70MHz/h), and as much as 700-MHz continuous frequency tuning of signal and idler are demonstrated.     

Experimental study of actively mode-locked semiconductor laser with grating external cavity

In this paper,complete mode-locking optical pulses have been obtained froman actively mode-locked GaAs/GaAlAs semiconductor laser with grating external cavity.Theshortest optical pulse is 7.3 ps measured by second harmonic generation(SHG)autocorrelator.The repetition rate is 995.12 MHz and the central wavelength is 798.4 nm.The effect ofmodulation frequency,modulation current,and bias current on the optical pulses width areinvestigated.     

在光致聚合物中采用脉冲激光记录全息图的记录条件研究

在蓝绿敏光致聚合物材料中,用532 nm激光器作为光源,在等光强不同重复频率和等重复频率不同光强条件下分别进行全息记录,用红光进行动态读出,获得两种记录条件下的衍射效率曲线.实验结果表明,在近连续脉冲光下进行全息记录时,较低重复频率和较低光强的脉冲激光能够明显提高光致聚合物光栅的最高衍射效率,通过优化脉冲激光的重复频率和平均光强,可以在材料中记录衍射效率最高的全息图.     

Stable and widely tunable all-fiber Pr(3+)-doped cw laser system using fiber Bragg gratings

A simple and strictly all-fiber 1300-nm cw laser is presented. It is tunable over 16 nm with 0.5-nm linewidth and several milliwatts of output power in the whole tuning range from 1292 to 1308 nm. The setup uses a fiber Bragg grating as a combined tuning element and narrow-band output mirror. The simplicity and stability of this system are due to the following two characteristics: First, polarization control is not necessary anywhere in the system, and second, a wavelength-selective system and a narrow-band mirror are combined into one novel fiber-optic element.     

Development of a high-power deep-ultraviolet continuous-wave coherent light source for laser cooling of silicon atoms

We developed a deep-UV single-mode coherent light source through two-stage highly efficient frequency conversions by use of external cavities. In the first stage, second-harmonic power of 500 mW was obtained by frequency doubling of a 746-nm Ti:sapphire laser with a conversion efficiency of 40%. In the second stage, 50-mW power at ~252nm was obtained by doubly resonant sum-frequency mixing of 373-nm light from the first-stage conversion and 780-nm light from a diode laser. The output performance of this deep-UV light source is sufficient for laser cooling of neutral silicon atoms.     

Quasi-phase-matched generation of tunable blue light in a quasi-periodic structure

We present what is to our knowledge a new approach to generating tunable blue light by cascaded nonlinear frequency conversion in a single LiTaO3 crystal. Simultaneous quasi-phase matching of an optical parametric generation process and a sum-frequency mixing process is achieved by means of structuring the crystal with a quasi-periodic optical superlattice. The spectral (wavelength tuning and bandwidth) and power characteristics of the blue-light generation are studied with a fixed-wavelength 532-nm picosecond laser and a wavelength-tunable nanosecond optical parametric oscillator (OPO) as the pump sources. By tuning the OPO wavelength, we could tune the blue output over approximately 20 nm. Temperature tuning of the blue output at a fixed pump wavelength of 532 nm was limited to approximately 1.5 nm. A maximum blue power of 15 microW was generated at a pump power of 0.5 mW, corresponding to an efficiency of 3%.     

Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4)

We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light.     

Tunable ultraviolet radiation by second-harmonic generation in periodically poled lithium tantalate

We describe electric-field poling of fine-pitch ferroelectric domain gratings in lithium tantalate and characterization of nonlinear-optical properties by single-pass quasi-phase-matched second-harmonic generation (QPM SHG). With a 7.5-microm-period grating, the observed effective nonlinear coefficient for first-order QPM SHG of 532-nm radiation is 9 pm/V, whereas for a grating with a 2.625-microm period, 2.6 pm/V was observed for second-order QPM SHG of 325-nm radiation. These values are 100% and 55% of the theoretically expected values, respectively. We derive a temperature-dependent Sellmeier equation for lithium tantalate that is valid deeper into the UV than currently available results, based on temperature-tuning experiments at different QPM grating periods combined with refractive-index data in the literature.     

Quadrature Frequency Conversion Scheme Using CsLiB6O10 Crystals for the Efficient Second-Harmonic Generation of High Power Nd:YAG Laser

The ability of CsLiB_6O10 (CLBO) crystals for high power second-harmonic generation (SHG) of a 1064-nm Nd:YAG laser in a quadrature arrangement was experimentally demonstrated. A 532-nm second harmonic output pulse energy of 2.25 J was obtained with 3.21 J of an input 1064-nm fundamental pulse energy at a repetition rate of 10 Hz, corresponding to a power conversion efficiency in excess of 70%.     

Compact, 220-ps visible laser employing single-pass, cascaded frequency conversion in monolithic periodically poled lithium niobate

We report the first demonstration to our knowledge of 220-ps visible laser generation from passively Q-switched-laser pumped periodically poled lithium niobate (PPLN) in a single-pass, cascaded frequency-conversion process. The monolithic PPLN consists of a 1-cm section for frequency doubling the 1064-nm Nd:YAG pump laser to a 532-nm laser and a subsequent 4-cm section for generating the visible laser in a 532-nm-pumped optical parametric generation (OPG) process. In generating the 622.3-nm OPG signal wavelength we measured a 3.0-microJ/pulse pump threshold at the 1064-nm wavelength, 16% overall efficiency, and 35% slope efficiency at two times threshold. At 10(-6) pump duty cycle and 20-mW average power in the visible, photorefractive damage was not observed at the phase-matching temperature of 40.3 degrees C.     

Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy

We present an experimental technique that permits mechanical-noise-free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532-nm frequency-doubled output from a Nd:YAG laser and an iodine vapor cell. The cell is placed in a folded ring cavity (FRC) with counterpropagating pump and probe beams. The FRC is locked with the Pound-Drever-Hall technique. Mechanical noise is rejected by differencing the pump and probe signals. In addition, this differenced error signal provides a sensitive measure of differential nonlinearity within the FRC.     

Efficient blue cw Nd:YAG microchip laser with two intracavity frequency doublers

A microchip cavity including a half-monolithic Nd:YAG- KNbO(3) chip and a second KNbO(3) crystal is presented. An output power of up to 30 mW at 473 nm pumped by a single stripe 1-W at 808-nm diode is achieved. The laser can be operated in either single-longitudinal or multilongitudinal mode by rotation of the second frequency-doubling crystal to 0 degrees or 90 degrees from the first one. The cw output noise is less than 2% for both cases.     

Holographic grating recorded by He–Ne laser operating at 632.8 nm in polymer film containing push–pull azo dye

Holographic gratings were optically recorded by two beams from a He–Ne laser operating at 632.8 nm in poly (methyl methacrylate) (PMMA) film containing push–pull azo dye. The holographic characteristics of the recorded gratings were dependent on the polarization direction of the recording beams and the relationship between the diffractive signals and the power density of recording beams was investigated. The formation of holographic gratings accompanied by 532 nm (double-frequency of Nd:YAG laser) irradiation was studied in detail. It was found that the effect of 532 nm laser to the holographic grating lay in two aspects. The acceleration effect of 532 nm laser to the formation of holographic grating is predominant when the power density of 532 nm laser is low. While at relatively high power density of 532 nm laser, the erasure is the main factor to the holographic grating. Moreover, the holographic grating was probed by 532 nm laser at low power density and the dependence of the first order diffractive signal on the recording beam power density was also presented.     

High-power parametric amplification of 11.8-fs laser pulses with carrier-envelope phase control

Phase-stable parametric chirped-pulse amplification of ultrashort pulses from a carrier-envelope phase-stabilized mode-locked Ti:sapphire oscillator (11.0 fs) to 0.25 mJ/pulse at 1 kHz is demonstrated. Compression with a grating compressor and a LCD shaper yields near-Fourier-limited 11.8-fs pulses with an energy of 0.12 mJ. The amplifier is pumped by 532-nm pulses from a synchronized mode-locked laser, Nd:YAG amplifier system. This approach is shown to be promising for the next generation of ultrafast amplifiers aimed at producing terawatt-level phase-controlled few-cycle laser pulses.     

A novel 852-nm tunable fiber laser

We report a novel fiber laser operating at 850-nm band by using semiconductor optical amplifier and fiber grating. The laser system is stable, compact, and the operating wavelength can be tuned continuously from about 851 to 854 nm for Cs atomic clock system by stretching the fiber grating. An output power up to 20 mW is obtained with a signal-to-background ratio beyond 20 dB.