All-solid-state doubly resonant sum-frequency continuous-wave laser at 555 nm

A new kind of resonator for doubly resonant continuous-wave (CW) intracavity sum-frequency mixing(SFM) is presented. A coherent radiation of 327 mW at 555 nm is generated by mixing 1342-nm Nd:YVO4 laser and 946-nm Nd:YAG laser. The M2 beam quality factor of the sum-frequency mixed yellow-green laser is less than 1.7. The low-noise characteristic of the yellow laser is demonitrated.     

All-solid-state continuous-wave doubly resonant all-intracavity sum-frequency mixer

A new resonator design for doubly resonant continuous-wave intracavity sum-frequency mixing is presented. We generated 212 mW of coherent radiation at 618 nm by mixing the radiation of a 1080-nm Nd(3+):YAlO(3) laser and a 1444-nm Nd(3+):YAG laser. Two different mixing resonator setups and several nonlinear-optical crystals were investigated. So far output is limited by unequal performance of the two fundamental lasers and coating problems of the nonlinear crystals.     

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.     

All solid-state CW orange-red laser at 620 nm

We report for the first time a continuous-wave (CW) orange-red radiation at 620 nm by intracavity sum-frequency generation of 1085-nm Nd:YVO₄ laser and 1444-nm Nd:YAG laser. Using type-II critical phase matching KTP crystal, 620-nm orange-red laser was obtained by 1085- and 1444-nm intra-cavity sum-frequency mixing, and output power of 223 mW was demonstrated. At the output power level of 223 mW, the output power stability is better than 3% and laser beam quality M ² factor is 1.32.     

Generation of tunable 187.9-196-nm radiation in beta-Ba(2)BO(4)

Tunable 187.9-196-nm vacuum-ultraviolet radiation was generated at room temperature in a beta barium borate crystal by sum-frequency mixing of Nd:YAG laser radiation and the second harmonic of a dye laser pumped by the second harmonic of the same Nd:YAG laser. By use of the advantageous noncollinear phase-matching configuration, a peak power of 1.3 kW was obtained at 194 nm with input power densities as low as 79MW/cm(2) for 1064-nm and 0.65MW/cm(2) for 237.3-nm radiation.     

Self-sum- and -difference-frequency mixing in GdAl(3)(BO(3))(4):Nd(3+) for generation of tunable ultraviolet and infrared radiation

We exploited Nd(3+) laser emission at 1061.9 nm ((4)F(3/2)?(4)I(11/2) channel) in a self-chi((2)) active GdAl(3)(BO(3))(4):Nd(3+) laser crystal. UV radiation was obtained from a 1.8% yield from self-sum-frequency mixing: 1/pump + 1/1061.9 = 1/UV, during pumping in the Nd(3+) (4)G(5/2)-(2)G(7/2) levels near 588 nm. The UV tunability had a range of 378-382 nm. We have demonstrated, for the first time to our knowledge, generation of coherent IR radiation from a self-difference-frequency mixing laser: 1/pump - 1/1061.9 = 1/IR. We got a 0.5% yield and tunability in the 1305-1365-nm range.     

Diode-laser-pumped continuous-wave doubly linear resonator sum-frequency mixing red laser at 689 nm

We report for the first time a coherent red radiation at 689 nm by intracavity sum-frequency generation of the 1319- and 1444-nm laser-lines of two Nd:YAG lasers. Using type-II critical phase matching KTP crystal, 689-nm red laser was obtained by 1444- and 1319-nm intra-cavity sum-frequency mixing, and output power of 156 mW was obtained. At the output power level of 156 mW, the output power stability is better than 5.0% and laser beam quality M ² factor is 1.23.     

Stimulated Raman scattering in a potassium titanyl phosphate crystal: simultaneous self-sum frequency mixing and self-frequency doubling

A potassium titanyl phosphate crystal is used to achieve efficient stimulated Raman scattering conversion with simultaneous self-sum frequency mixing and self-frequency doubling. Inside a diode-pumped Nd:YAG Q-switched laser cavity, 1.03 W of 1129-nm second Stokes average output power and 0.25 W of 548-nm sum-frequency average power are simultaneously generated with a diode input power of 10 W at a pulse repetition rate of 10 kHz.     

Efficient cooling and trapping of strontium atoms

We report the capture of cold strontium atoms in a magneto-optical trap (MOT) at a rate of 4 x 10(10) atoms/s. The MOT is loaded from an atomic beam decelerated by a Zeeman slower operating with a focused laser beam. The 461-nm laser, used for both cooling and trapping, was generated by sum-frequency mixing in a KTP crystal with diode lasers at 813 nm and a Nd:YAG laser at 1064 nm. As much as 115 mW of blue light was obtained.     

Diode-laser-based ultraviolet-absorption sensor for high-speed detection of the hydroxyl radical

A new diode-laser-based UV-absorption sensor for high-speed detection of the hydroxyl radical (OH) is described. The sensor is based on sum-frequency generation of UV radiation at 313.5 nm by mixing the output of a 763-nm distributed-feedback diode laser with that of a 532-nm high-power, diode-pumped, frequency-doubled Nd:YVO4 laser in a beta-barium borate crystal. Approximately 25 microW of UV radiation is generated and used to probe rotational transitions in the A2 Sigma+ -X2II (v' = 0, v" = 0) electronic transition of OH. Single-sweep, single-pass measurements of temperature and OH concentration in a stoichiometric C2H4-air flame are demonstrated at rates up to 20 kHz.     

Self-optical parametric oscillation in periodically poled neodymium-doped lithium niobate

Self-optical parametric oscillation is demonstrated for the first time to our knowledge in a periodically poled neodymium-doped lithium niobate (Nd:PPLN) crystal. The crystal is pumped by a cw Ti:sapphire laser at 813.5 nm. The Nd(3+) ions absorb the 813.5-nm radiation to generate 1084-nm laser oscillation. The internally Q switched 1084-nm radiation pumps the periodically poled lithium niobate host matrix to generate optical parametric oscillation at 1.55 and 3.6 microm . Up to 24% conversion efficiency from laser to signal is observed.     

Frequency stabilization of a 1319-nm Nd:YAG laser by saturation spectroscopy of molecular iodine

Hyperfine transitions of molecular iodine were observed by use of the frequency-doubled output of a 1319-nm Nd:YAG laser with saturation spectroscopy. The laser frequency was stabilized to the observed hyperfine transition and reached a stability of 6 x 10(-12) for a 1.5-s averaging time, improving toward the 1 x 10(-12) level after 100 s. The iodine-stabilized 1319-nm Nd:YAG laser is an excellent candidate for an optical frequency standard for telecommunication applications.     

Highly efficient Nd:YAG/LBO laser at 473 nm under direct 885-nm diode laser pumping

<正>In diode pumped Nd:YAG lasers,the quantum defect is the most important parameter determining the thermal load of the laser crystal,which can be dramatically reduced by pumping directly into the upper laser level.A compact folded three-mirror cavity with a length of 105 mm is optimized to obtain a highly efficient 473-nm laser.When the absorbed pump power(with 15.8-W incident pump power) at 885 nm into Nd:YAG is 10 W,a continuous-wave 473-nm blue laser as high as 2.34 W is achieved by LBO intra-cavity frequency doubled.The optical-to-optical conversion efficiency is 14.8%.To the best of our knowledge, this is the highest efficiency at 473 nm by an intra-cavity doubled frequency Nd:YAG laser.     

A linearly polarized continuous-wave 1357-nm Nd:YAG laser

We demonstrated a linearly polarized continuous-wave Nd:YAG laser operating at a 1357-nm single-wavelength, by a 808-nm diode as an end-pump source. We chose a Brewster-angle-cut Nd:YAG laser host crystal, due to its two salient features as follow: linearly polarized laser output and single-wavelength oscillation can be easily obtained. In this paper, a continuous-wave all-solid-state single-wavelength laser operating at 1357 nm is demonstrated with a diode-end-pumped Brewster-cut Nd:YAG laser. The laser had a 1.03-W maximum output power under an incident pump power of 15.0 W, a 12.7% slope efficiency, a 6.9% optical-to-optical conversion efficiency, a 0.14-nm spectral linewidth and a 3% power-output stability within 30 min. PACS 42.55.Rz; 42.55.Xi; 42.70.Hj     

Efficient Nd:YVO_4 laser in-band pumped by wavelength-locked 913.9-nm laser diode and Q-switch operation

An efficient 1064-nm Nd:YVO_4laser in-band pumped by a wavelength-locked laser diode(LD) at 913.9 nm was demonstrated. The maximum continuous wave(CW) output power of 23.4 W at 1064 nm was realized with the incident pump power of 40 W, corresponding to a total optical-to-optical efficiency of 58.5%. This is to the best of our knowledge the highest total optical-to-optical efficiency and output power of Nd:YVO_4laser in-band pumped by a 913.9-nm laser diode.The Q-switched operation of this laser was also investigated. Through a contrast experiment of pumping at 808 nm, the experimental results showed that an Nd:YVO_4laser in-band pumped by a wavelength-locked LD at 913.9 nm had excellent pulse stability and beam quality for high repetition rate Q-switching operation.     

High power and highly efficient Nd:YAG laser emitting at 1123 nm

A diode-end-pumped continuous-wave (CW) Nd:YAG laser emitting at 1123 nm is realized efficiently in a 25-mm-long cavity. A composite Nd:YAG (cNd:YAG) crystal is selected as the gain medium. With an incident diode power of 26.1 W, an output power of up to 9.3 W is obtained, corresponding to an optical-to-optical conversion efficiency of 35.6%. The laser performances at 1123 nm are compared between composite Nd:YAG and common Nd:YAG crystals. The results show that composite Nd:YAG is a better choice for 1123-nm laser generations.     

Generation of femtosecond radiation at 211 nm by femtosecond pulse upconversion in the field of a picosecond pulse

We show that, in the case of sum-frequency mixing, one can alleviate group-velocity mismatch between IR and UV pulses by choosing different pulse widths, thus extending the interaction length of ultrashort pulses within nonlinear crystals. By fifth-harmonic generation with a Nd:glass laser, we demonstrate efficient frequency upconversion of 195-fs 264-nm pulses under the envelope of 0.9-ps 1055-nm pulses in beta-barium borate crystal, yielding <270-fs pulses with energy of up to 110muJ at 211 nm.     

Compact, efficient diode-end-pumped Nd:GdVO4 slab continuous-wave 912-nm laser

A fiber-coupled laser-diode (LD) end-pumped Nd:GdVO₄ slab continuous-wave (CW) 912-nm laser and an LD bar end-pumped Nd:GdVO₄ slab CW 912-nm laser are both demonstrated in this paper. Using the fiber-coupled LD of end-pumped type, a highest CW 912-nm laser output power of 10.17 W is obtained with a high optical-to-optical conversion efficiency of 24.6% and a slope efficiency of 34.5%. The measured M² factors of beam quality in x and y directions are 5.3 and 5.1, respectively. Besides, an LD bar of end-pumped type is used to realize CW 912-nm laser output, which has the advantages of compactness and low cost. When the pump power is 38.8 W, the output power is 8.87 W and the measured M² factors of beam quality in x and y directions are 16 and 1.31, respectively. In order to improve the beam quality of the 912-nm laser at x direction, a new quasi-concentric laser resonator will be designed, and an LD bar end-pumped Nd:GdVO₄ slab high-power CW 912-nm TEM₀₀ laser will be realized in the future.     

Performance of a low-loss pulsed-laser-deposited Nd:Gd(3) Ga(5)O(12) waveguide laser at 1.06 and 0.94 mum

We report the laser performance of a low-propagation-loss neodymium-doped Gd(3)Ga(5)O(12) (Nd:GGG) waveguide fabricated by pulsed-laser deposition. An 8- mum -thick crystalline Nd:GGG film grown upon an undoped Y(3)Al(5)O(12) substrate lases at 1.060 and 1.062 microm when pumped by a Ti:sapphire laser operating at 740 or 808nm.Using a 2.2% output coupler, we observed a 1060-nm laser threshold of 4mW and a slope efficiency of 20%. Laser action was also achieved, for what we believe is the first time in Nd:GGG, on the quasi-three-level 937-nm transition. With a 2% output coupler at this wavelength a laser threshold of 17mW and a 20% slope efficiency were obtained. This demonstration of low propagation loss combined with the fact that these waveguides have a very high numerical aperture (0.75) makes pulsed-laser-deposited thin films attractive for high-power diode-pumped devices.     

Diode-pumped 1123-nm Nd:YAG laser

We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbOa (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.