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.     

Generation of 99-mW continuous-wave 285-nm radiation for magneto-optical trapping of Mg atoms

We have developed a tunable intense narrow-band 285 nm light source based on frequency doubling of 570 nm light in BBO. At input powers of 840 mW (including 130 mW used for locking purposes) we generate 99 mW UV radiation with an intensity profile suitable for laser-cooling experiments. The light is used for laser cooling of neutral magnesium atoms in a magneto-optical trap (MOT). We capture about 5×10⁶ atoms directly from a thermal beam and find that the major loss mechanism of the magnesium MOT is a near-resonant two-photon ionization process. Received: 15 February 2002 / Revised version: 13 August 2002 / Published online: 11 December 2002 RID="*" ID="*"Corresponding author. Fax: +45-4588/7762, E-mail: dnm@mic.dtu.dk Present address: Mikroelektronik Centret, Technical University of Denmark, Orsteds Plads, Bldg. 345 East, 2800 Kgs. Lyngby, Denmark     

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.     

500.5-nm blue-green laser based on sum-frequency mixing of diode pumped neodymium lasers

We report for the first time a continuous-wave (CW) coherent radiation at 500.5 nm by intracavity sum-frequency generation of 1063 nm Nd:GdVO₄ laser and 946 nm Nd:YAG laser. Blue-green laser is obtained by using a doubly cavity, type-II critical phase matching KTiOPO₄ (KTP) crystal sum-frequency mixing. With total pump power of 27.8 W, TEM₀₀ mode blue-green laser at 500.5 nm of 421 mW is obtained. At the output power level of 421 mW, the blue-green power stability is better than 2.8% and laser beam quality M ² factor is 1.37.     

CW coherent VUV radiation generated by resonant sum-frequency mixing in metal vapors

Resonant third-order sum-frequency mixing of continuous-wave visible and ultraviolet laser light is investigated in the metal vapors of Sr, Ca, Mg, and Zn. The laser radiation (with the frequencies ₁, ₂, and ₃) is generated by single-mode dye- and argonion lasers. The third-order nonlinear susceptibility is enhanced by tuning the laser frequencies 2₁ or ₁+₂ to a two-photon resonance. The wavelength of the generated coherent VUV radiation (with the frequency _VUV=3₁, _VUV=2₁+₂ or _VUV=₁+₂+₃) is tunable in spectral regions between 133 and 217 nm. For most conversion processes an additional enhancement of the nonlinearity is provided by an autoionizing level or by a highly excited state close to E=_VUV. With laser powers of 0.2–3 W the power of the generated sum frequencies is in the range of 5×10⁵–6×10¹⁰ photons s^–1 (0.5 pW–60 nW).     

551 nm Generation by sum-frequency mixing of intracavity pumped Nd:YAG laser

We present for the first time a Nd:YAG laser emitting at 1319 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1319 nm intracavity pumped at 946 nm. Intracavity sumfrequency mixing at 946 and 1319 nm was then realized in a LBO crystal to reach the yellow range. We obtained a continuous-wave output power of 158 mW at 551 nm with a pump laser diode emitting 18.7 W at 809 nm.     

589-nm yellow laser generation by intra-cavity sum-frequency mixing in a T-shaped Nd:YAG laser cavity

To obtain high power 589-nm yellow laser, a T-shaped thermal-insensitive cavity is designed. The optimal power ratio of 1064- and 1319-nm beams is considered and the fundamental spot size distribution from the output mirror to the two laser rods are calculated and simulated, respectively. As a result, a 589-nm yellow laser with the average output power of 5.7 W is obtained in the experiment when the total pumping power is 695 W. The optical-to-optical conversion efficiency from the fundamental waves to the sum frequency generation is about 15.2% and the pulse width is 150 ns at the repetition rate of 18 kHz. The instability of the yellow laser is also measured, which is less than 2% within 3 h. The beam quality factors are Mx^2 = 4.96 and My^2 = 5.08.     

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.     

High-power continuous-wave doubly resonant all-intracavity sum-frequency mixing deep blue laser at 447 nm

In this paper, a high-power continuous-wave deep blue laser at 447 nm with intracavity tripling was achieved. The deep blue laser at 447 nm is obtained by using a doubly cavity, and type-II critical phase matching KTP crystal for intracavity sum-frequency mixing. Through designing of the cavity, the optimum matching of modes and gains for the two wavelengths was obtained. With incident pump power of 30 W for the Nd:YVO₄ crystal and 16 W for the other Nd:YVO₄ crystal, the deep blue laser output of 3.5 W at 447 nm with TEM₀₀ mode was obtained, the beam quality M² value was equal to 1.8 in both horizontal and vertical directions at the maximum output power, and the power stability is better than 3% at the maximum output power during half an hour. The experimental results show that the intracavity sum-frequency mixing by doubly resonant is an effective method for high-power blue laser.     

20 W of continuous-wave sodium D2 resonance radiation from sum-frequency generation with injection-locked lasers

A 20-W all-solid-state continuous-wave single-frequency source tuned to the sodium D2a line at 589.159 nm has been developed for adaptive optical systems. This source is based on sum-frequency mixing two injection-locked Nd:YAG lasers in lithium triborate in a doubly resonant external cavity. Injection locking the Nd:YAG lasers not only ensures single-frequency operation but also allows the use of a single rf local oscillator for Pound-Drever-Hall locking both the injection-slave and the sum-frequency cavities. We observe power-conversion efficiencies in excess of 55% and a linearly polarized diffraction-limited output tunable across the sodium D2 line (589.156 to 589.160 nm) with no change in output power and with high amplitude and pointing stability.     

Compact 584-nm light source based on sum-frequency mixing of diode pumped Nd:YLF lasers

A dual-wavelength continuous-wave (CW) diode end-pumped Nd:YLiF₄ (Nd:YLF) laser that generates simultaneous laser action at the wavelengths 1047 and 1321 nm is demonstrated. A total output power of 350 mW for the dual-wavelength was achieved. Furthermore, intracavity sum-frequency mixing at 1047 and 1321 nm was then realized in a LBO crystal to reach the yellow-green range. We obtained a total CW output power of 34 mW at 584 nm.     

Efficient sum-frequency mixing through transparency induced by autoionization

It is shown that efficient sum-frequency mixing is possible through transparency induced by autoionization. Tuning the incident laser frequencies to the absorption minimum of an autoionizing resonance for the generated wave greatly reduces the linear absorption of the generated wave while third-order susceptibility is still enhanced. The proposed scheme does not require any strong radiative couplings and would be particularly useful for the generation of short-wavelength radiation.     

Generation of tunable cw infrared radiation by difference frequency mixing

Tunable cw infrared radiation has been generated by noncollinear difference frequency mixing in LiIO₃, using the output of an argon ion laser at 514 nm or 488 nm and the intracavity radiation of a Rhodamine 6 G dye laser. Infrared powers up to 4 μW in multimode and 0.5 μW in single-mode operation tunable in the range of 2.3 μm to 4.6 μm have been obtained. Properties and possibilities of the noncollinear mixing geometry and the intracavity mixing system are discussed.     

3.62 W of continuous-wave orange-yellow light generated by intra-cavity sum-frequency mixing of Nd:YVO4

A design of laser-diode array (LDA) end-pumped Nd:YVO₄ laser that generates simultaneous laser action at wavelengths 1064 and 1342 nm is presented. Using type-I critical phase matching (CPM) BiB₃O₆, 593.5 nm continuous-wave (cw) Orange-yellow laser is obtained by 1064 nm and 1342 nm in an intra-cavity sum-frequency mixing. The maximum laser output power of 3.62 W is obtained when an incident pump laser of 27.5 W is used. The optical-to-optical conversion is up to 13.2%. To the best of our knowledge, this is the highest conversion efficiency at 593.5 nm in an intra-cavity sum-frequency Nd:YVO₄ laser.     

480-nm blue laser based on sum-frequency mixing of diode pumped Nd:ASL-Yb:YAG lasers

We report for the first time a continuous-wave (CW) coherent radiation at 480 nm by intracavity sum-frequency generation of 900 nm Neodymium Doped Strontium and Lanthanum Aluminate (Nd:ASL) laser and 1030 nm Yb:Y₃Al₅O₁₂ (Yb:YAG) laser. Blue laser is obtained by using a doubly cavity, type-I critical phase matching LiB₃O₅ (LBO) crystal sum-frequency mixing. With total pump power of 28.6 W, the blue laser at 480 nm of 170 mW is obtained. At the output power level of 170 mW, the blue power stability is better than 4.7% and laser beam quality M ² factor is 1.43.     

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 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.     

Generation of phase-locked and tunable continuous-wave radiation in the terahertz regime

Broadly tunable phase-stable single-frequency terahertz radiation is generated with an optical heterodyne photomixer. The photomixer is excited by two near-infrared CW diode lasers that are phase locked to the stabilized optical frequency comb of a femtosecond titanium:sapphire laser. The terahertz radiation emitted by the photomixer is downconverted into RF frequencies with a waveguide harmonic mixer and measurement-limited linewidths at the Hertz level are demonstrated.     

Generation of mid-infrared radiation by self-difference frequency mixing in chromium-doped zinc selenide

We report what we believe to be the first demonstration of mid-infrared generation (approximately 9 microm) by self-difference frequency generation in Fresnel birefringence quasi-phase-matched Cr:ZnSe laser slabs.     

Nonresonant tripling and sum-frequency mixing in Hg

Nonresonant frequency tripling and sum-frequency mixing of pulsed dye-laser radiation generates in Hg vapor continuously tunable coherent vuv radiation in the wavelength range _vuv=132-185nm. Laser pulse powers of 1–2 MW produce vuv light pulses of 0.6–1.5 W (2–4.8×10⁹ photons/pulse).