High-power,blue-light generation in a dual-structure,periodically poled,stoichiometric LiTaO<Subscript>3</Subscript> crystal

High-power blue light was generated from a diode-side-pumped Q-switched 1319 nm Nd:YAG laser with a periodically poled, stoichiometric LiTaO₃ (PPSLT) crystal. The PPSLT sample used in this experiment consists of two segments in series: the first segment has a period of 14.08 μm for the second harmonic generation (SHG) and the second segment has periods of around 4.6 μm for the generation of blue light by mixing fundamental and SH. An average power of 466 mW of a 440 nm blue light was obtained at the fundamental power of ∼5.4 W with a conversion efficiency of 8.6%. The output power fluctuated by 3% over a half-hour period. This result indicates that our scheme is a practical method to construct a reliable compact blue laser. PACS 42.70.Mp; 42.79.Nv; 42.55.Xi     

Quasi-monolithic ring resonator for efficient frequency doubling of an external cavity diode laser

A quasi-monolithic second-harmonic-generation ring resonator assembled with miniaturized components is presented. The ring contains a 10-mm-long bulk periodically poled lithium niobate crystal for second-harmonic generation, four plane mirrors and two gradient-index lenses. All parts are mounted on a glass substrate with an overall size of 19.5 mm×8.5 mm×4 mm. As pump source a broad-area laser diode operated in an external resonator with Littrow arrangement is utilized. This external cavity diode laser provides near diffraction limited, narrow-bandwidth emission with an optical output power of 450 mW at a wavelength of 976 nm. Locking of the diode laser emission to the resonance frequency of the ring cavity was achieved by an optical self-injection locking technique. With this setup more than 126 mW of diffraction-limited blue light at 488 nm could be generated. The opto–optical conversion efficiency was 28% and a wall plug efficiency better than 5.5% could be achieved.     

Second-harmonic generation of light at 544 and 272 nm from an ytterbium-doped distributed-feedback fiber laser

We report external cavity second-harmonic generation of light at 544 and 272 nm based on an ytterbium-doped distributed-feedback fiber laser. The nonlinear crystal used to generate light at 544 nm is LiNbO3, and the maximum output of the cavity is 845 mW, corresponding to a conversion efficiency of 55%. In a second frequency-doubling step, using a beta-BaBa2O4 crystal, we generate up to 115 mW of light at 272 nm with a conversion efficiency of 14%.     

Highly efficient single-pass frequency doubling of a continuous-wave distributed feedback laser diode using a PPLN waveguide crystal at 488 nm

A continuous-wave distributed feedback diode laser emitting at 976 nm was frequency doubled by the use of a periodically poled lithium niobate waveguide crystal with a channel size of 3 microm x 5 microm and an interaction length of 10 mm. A laser to waveguide coupling efficiency of 75% could be achieved resulting in 304 mW of incident infrared light inside the waveguide. Blue laser light emission of 159 mW at 488 nm has been generated, which equals to a conversion efficiency of 52%. The resulting wall plug efficiency was 7.4%.     

Low-threshold mid-infrared optical parametric oscillation in periodically poled LiNbO3 synchronously pumped by a Ti:sapphire laser

We report the generation of tunable high-repetition-rate optical pulses in the mid-infrared using synchronously pumped parametric oscillation in periodically poled LiNbO₃ (PPLN). Using a Kerr-lens-mode-locked Ti:sapphire laser as the pump source and a PPLN crystal incorporating grating periods of 21.0–22.4 μm, we have achieved wavelength conversion in the -–4 6μm spectral range in the mid-infrared. The use of a semi-monolithic cavity design and hemispherical focusing has permitted pulse generation in the strong idler absorption region of PPLN, resulting in a simple, compact, all-solid-state configuration with a pump power threshold as low as 17 mW and mid-infrared idler powers of up to 64 mW at 9% extraction efficiency. Signal output powers of up to 280 mW at 35% extraction efficiency are available over the -–1.004 1.140μm spectral range at 80.5 MHz and pulse repetition rates at harmonics of the fundamental frequency up to 322 MHz have also been obtained. Received: 5 December 2000 / Revised version: 23 January 2001 / Published online: 27 April 2001     

High-power ps InGaAs diode laser MOPA system for efficient frequency doubling in periodically poled KTP

This paper reports on a mode-locked InGaAs master oscillator power amplifier (MOPA) system that generates at 920 nm 14-ps-long pulses with a repetition rate of 4.3 GHz and an average power of 2.7 W. Single-pass frequency doubling in a periodically poled KTP crystal provides 550 mW of blue 460-nm radiation. The power of the blue output, which corresponds to a conversion efficiency of more than 20%, was optimized by a detailed investigation of the influence of various system parameters like injection current and repetition rate on pulse power, pulse duration, and spectral shape of the infrared laser pulses. PACS 42.65.Ky; 42.55.Px; 42.72.Bj     

Generation of 840 mW of red light by frequency doubling a diode-pumped 1342 nm Nd:YVO4 laser with periodically-poled LiTaO3

We report an efficient generation of red light in a periodically-poled LiTaO₃ (PPLT) crystal by extracavity single-pass frequency doubling of a diode-pumped, Q-switched Nd:YVO₄ laser at 1342 nm. The sample used in the experiment is 20 mm in length and 14.77 μm in period. An average power of 840 mW of the 671 nm red light is obtained with a 808 nm pump of 12.3 W, the overall optical-to-optical efficiency being 6.8%. The measured effective nonlinear coefficient of the sample is ∼3.8 pm/V. The high conversion efficiency and output power demonstrate that the periodically-poled crystal serving as a frequency conversion device may be used in practice to construct an all-solid-state red laser based on an extracavity single-pass quasi-continuous scheme. Received: 17 September 2001 / Revised version: 23 January 2002 / Published online: 8 May 2002     

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%.     

Intracavity frequency-doubled green vertical external cavity surface emitting laser

An intracavity frequency-doubled vertical external cavity surface emitting laser (VECSEL) with green light is demonstrated. The fundamental frequency laser cavity consists of a distributed Bragg reflector (DBR) of the gain chip and an external mirror. A 12-mW frequency-doubled output has been reached at 540 nm with a nonlinear crystal LBO when the fundamental frequency output is 44 mW at 1080 nm. The frequency doubling efficiency is about 30%.     

Single-frequency cw vertical external cavity surface emitting semiconductor laser at 1003 nm and 501 nm by intracavity frequency doubling

This work reports single-frequency laser oscillation at λ=1003.4 nm of a diode-pumped vertical external cavity surface-emitting semiconductor laser for metrological applications. A low thermal resistance of the semiconductor active component is achieved by solid-liquid interdiffusion bonding onto a SiC substrate. The spectro-temporal dynamics of the laser is theoretically studied. Experimentally, an output power of 1.7 W is demonstrated in free running operation, and up to 500 mW in a true single longitudinal mode. Furthermore, single-frequency laser emission at λ=501.7 nm is obtained by intracavity frequency doubling, resulting in a total output power as high as 62 mW. PACS 42.55.Px; 42.55.Xi; 42.62.Eh; 42.65.Ky     

A narrow-line-width external cavity quantum dot laser for high-resolution spectroscopy in the near-infrared and yellow spectral ranges

We demonstrate a diode laser system which is suitable for high-resolution spectroscopy in the 1.2 μm and yellow spectral ranges. It is based on a two-facet quantum dot chip in a Littrow-type external cavity configuration. The laser is tunable in the range 1125–1280 nm, with an output power of more than 200 mW, and exhibits a free-running line width of 200 kHz. Amplitude and frequency noise were characterized, including the dependence of the frequency noise on the cavity length. Frequency stabilization to a high-finesse reference cavity is demonstrated, whereby the line width was reduced to approx. 30 kHz. Using a femtosecond frequency comb, the residual frequency instability was determined and found to be below 300 Hz on the time scales 1–300 s. Yellow light (>3 mW) at 578 nm was generated by frequency doubling in an enhancement cavity containing a PPLN crystal. The source has potential application for precision spectroscopy of ultra-cold Yb atoms and cold molecular hydrogen ions.     

紧凑型LD端面抽运Nd:YAG内腔三倍频准连续355 nm紫外激光器

报道了一台LD端面抽运Nd:YAG晶体内腔三倍频355 nm激光高效率、高峰值功率准连续输出的全固态紫外激光器.激光腔采用紧凑型平平直腔,腔长仅106 mm.当注入抽运功率为5.73 W、重复频率为9 kHz时,获得163 mW的355 nm激光准连续输出,光光转换效率达到最高2.84％.当注入抽运功率为6.7 W重复频率为5 kHz时,获得最高174 mW的355 nm激光准连续输出,输出功率短期不稳定性为5％,光束质量因子M²为3.79.当注入抽运功率为5.73 W、重复频率为2 kHz时,获得112 mW的355 nm激光准连续输出,峰值功率最高达到9.15 kW.通过采用内腔倍频技术和设计合理的腔结构,实现了中小功率准连续输出的全固态紫外激光器的小型化、便携化,进一步拓宽了紫外激光器的应用领域. 关键词： LD端面抽运 内腔三倍频 Q')" href="#">声光调Q 紫外激光     

Orange light generation from a PPKTP waveguide end pumped by a cw quantum-dot tunable laser diode

A compact all-room-temperature frequency-doubling scheme generating cw orange light with a periodically poled potassium titanyl phosphate waveguide and a quantum-dot external cavity diode laser is demonstrated. A frequency-doubled power of up to 4.3 mW at the wavelength of 612.9 nm with a conversion efficiency exceeding 10% is reported. Second harmonic wavelength tuning between 612.9 nm and 616.3 nm by changing the temperature of the crystal is also demonstrated.     

Generation of red light at 660 nm by frequency doubling a Nd:YAG laser with periodically-poled stoichiometric LiTaO<Subscript>3</Subscript>

High power red light was generated from a periodically-poled stoichiometric LiTaO₃ (PPSLT) by single-pass frequency doubling of a diode-side-pumped, Q-switched Nd:YAG laser at 1319 nm. An average power of 2.4 W of the 660 nm red light was obtained at the fundamental power of ∼5.4 W with the conversion efficiency up to 44.4% and with low fluctuation down to 2%. The high efficiency and stability at the red output indicate that it is a practical method to construct a reliable compact red laser. PACS 42.70.Mp; 42.79.Nv; 42.55.Xi     

Diode-pumped high-power cw blue laser at 473 nm with a compact three-element cavity

We report on a diode-pumped cw Nd:YAG laser operating at 946 nm with a maximum output power of 3.3 W and a slope efficiency of 22% with respect to the incident pump power of 17.5 W. Intracavity frequency doubling with nonlinear crystal LBO yielded a single-ended blue output power of 590 mW with optical conversion efficiency of 3.4%. A very simple, compact three-element cavity of 35 mm long was used. The power fluctuation of the blue laser was 4.3% (rms) at output power level of 400 mW. Transverse mode hopping was observed at higher output power.     

Completely solid-state LD-side-pumped Nd:YAlO<Subscript>3</Subscript> CW blue laser with intracavity frequency tripling

We report a completely solid-state continuous-wave (CW) blue laser operating at 447 nm utilizing intracavity frequency tripling of an LD-side-pumped Nd:YAlO₃ (Nd:YAP) laser operating at 1341.4 nm. An LBO crystal with type-I critical phase matching and a KTP crystal with type-II critical phase matching (CTM) were used for the second harmonic generation (SHG) and the third harmonic generation (THG), respectively. In view of the analysis of the cavity stability, a four-mirror folded cavity was designed and the output characteristics were theoretically analyzed. Experimental characteristics obtained were shown to be in agreement with the theoretical analysis. The maximum output power of the 447 nm CW blue laser reached 114 mW, which corresponds to a red-to-blue conversion efficiency of 9%.     

Efficient green generation by intracavity frequency doubling of an optically pumped semiconductor disk laser

We report the use of bismuth borate for efficient intracavity frequency doubling of an optically pumped semiconductor disk laser. An output power of 220 mW at 529 nm at room temperature has been demonstrated, corresponding to 52% conversion efficiency with respect to the fundamental power. The results are compared to frequency doubling with a potassium titanyl phosphate nonlinear crystal. PACS 42.55.Px; 42.70.Mp; 42.72.Bj     

High-repetition-rate eye-safe intracavity KTA OPO driven by a diode-end-pumped Q-switched Nd:YVO4 laser

An eye-safe, high-repetition-rate, single-resonant nanosecond intracavity optical parametric oscillator (IOPO), based on a non-critically phase-matched KTA crystal driven by a diode-end-pumped acousto-optically Q-switchedNd:YVO4 laser, was demonstrated for the first time to our knowledge. With an absorbed pump power of 11.3 W, 1.1 W average power and 2.5 ns pulse width at the signal (1534 nm) wavelength for 30-kHz repetition rate are synchronously achieved with the 25 mm long KTA crystal. The corresponding peak power and single pulse energy are estimated to be up to 14.7 kW and 36.7 μJ. The conversion efficiency from diode laser power to OPO signal output power was 9.8% and the corresponding slope efficiency was 15.4%. PACS 42.60.Gd; 42.65.Yj; 42.55.Xi     

Resonant frequency doubling of an actively mode-locked Ti: Al2O3 laser using an external enhancement cavity

We report on the efficient frequency doubling of an actively mode-locked Ti: Al₂O₃ laser. The laser output was in the form of pulses of 6–15 ps duration at a 240 MHz repetition rate, tunable from 737 nm to 806 nm. Using a 7 mm long Brewster cut crystal of LiIO₃ we have measured conversion efficiencies of up to 42% in the form of picosecond pulses tunable from 369–403 nm. The maximum generated power in the blue was 194 mW at 381 nm.     

Highly efficient blue-light generation from a compact, diode-pumped femtosecond laser by use of a periodically poled KTP waveguide crystal

We present a simplified, potentially portable, and highly efficient blue-light source from a periodically poled KTP waveguide crystal with a compact femtosecond Cr:LiSAF laser. This light source generates 5.6 mW of blue average output power at 424 nm with 27 mW of incident fundamental in a single-pass extracavity arrangement at room temperature. The overall system efficiency of electrical power to blue light is 0.5%, and the internal second-harmonic generation conversion efficiency is as high as 37%. The slope efficiency of 5.5% pJ(-1) at low pulse energies is, to our knowledge, the highest slope efficiency yet reported for frequency conversion into the blue spectral region.