A time-compensated spectral filter for transform-limited tunable picosecond pulse generation from spectro-temporal-selection dye lasers

Diffraction and transform-limited picosecond tunable pulses are generated from Spectro-temporal-Selection (STS) dye lasers by using a new extra-cavity filter. This filter is based on a grazing-incident grating and arranged in the configuration of a folded dispersive delay line. Thus, it provides both high spectral selectivity and controllable temporal compensation for elimination of pulse broadening. Direct production of diffraction- and transform-limited picosecond dye laser (10 µJ, 50 ps) pulses spectrally adjustable between 398 and 702 nm is demonstrated in a compact device, with 8 ns pump pulses from a nanosecond nitrogen laser.     

Spectrally Adjustable Picosecond Dye Laser Pulses Generated with Nanosecond Nitrogen Lasers

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Tunable sub-100 femtosecond dye-laser pulses generated with a nanosecond pulsed pumping

Subpicosecond pulses at a fixed wavelength produced with a low-Q cavity dye laser pumped by a single, nanosecond laser (Q-switched Nd:YAG) are converted into tunable high-power sub-100 femtosecond pulses by generation, spectral selection, amplification and compression of a supercontinuum. The tunable, chirped, high-energy pulses obtained are compressed with a prism pair. Energies up to 50 J in sub-100 fs pulses were obtained in the 540 to 650 nm range using 40 mJ of the Nd: YAG-laser pumping pulses at 532 nm. The whole sub-100 fs system including the low-Q dye laser uses only one Nd:YAG laser as a pump source.     

Direct Generation of Tunable UV Picosecond Laser Pulses Using Spectrotemporal Selection

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Simple generation of 400–700 nm picosecond dye laser pulses with nanosecond laser pumping

New results in the experimental study of the spectro-temporal selection (STS) method to produce picosecond dye laser pulses are presented. Adjustability of the picosecond pulse wavelength, possibility of extension of the STS method to different dyes and to UV pump wavelength, stability of the output pulse duration and intensity, and the concentration effect on pulse duration, are reported for the first time. From these results, production of high power picosecond (50–100 ps) dye laser pulses spectrally adjustable between 400 and 700 nm is obtained with a standard nanosecond pump laser, in a compact and simple device.     

Generation of tunable picosecond pulses in a simple distributed feedback dye laser under N2-laser pumping

Simple possibility of single tunable picosecond pulse generation in a conventional inexpensive distributed feedback dye laser (DFDL) is demonstrated. It is shown that when a TEA N₂-laser is used for pumping no diffraction grating is necessary in the DFDL optical scheme for operation in the picosecond regime. Hence wide-range spectral tuning from 357 to 665 nm was easily achieved. When pumped with a 0.6 ns 40 kW pulse of the TEA N₂-laser the DFDL generated pulses as short as 7 ps with time-bandwidth product better than 0.6 and peak power ? 10 kW. At a repetition rate of 50 pps the shot-to-shot energy stability of a single picosecond pulse was ±18% at ±7% stability of the TEA N₂-laser.     

Efficient generation of tunable VUV laser radiation below 205 nm by SFM in BBO

Design and performance characteristics of a tunable dye laser system for sum frequency mixing (SFM) in a BBO crystal are presented. The system is composed of two tunable pulsed dye lasers pumped synchronously by the second harmonic of a commercial Nd:YAG laser. The radiation produced by the first dye laser is frequency doubled by second-harmonic generation (SHG) in KDP and subsequently mixed by SFM in BBO with the light of the second dye laser. The interest was focussed on generation of tunable laser radiation below 205 nm with high output power and long-time wavelength stability. High conversion efficiencies enable output energies of 100 J (20 kW) at 196 nm using only moderate Nd:YAG pump energies of 67 mJ. Altogether, a laser system with very good specifications for analytical application in the near VUV spectral region is reported.     

A self-quenching picosecond distributed feedback dye laser pumped by a picosecond laser pulse

A tunable single short pulse laser system with a transform–limited bandwidth pumped by a picosecond Nd:YAG laser (ca. 120 ps pulse width) is demonstrated. With this configuration, the relaxation oscillations coming from a distributed feedback dye laser cavity are completely removed. Because the pumping pulsewidth is shorter than the lifetime of dye molecule on the upper laser state, the gain of the laser medium is depleted by the first pulse. The laser wavelength could be precisely tuned with the transform-limited bandwidth (for example, a linewidth of 0.02 nm). After amplification, we obtain a single short laser pulse energy up to 500 μJ at the pulsewidth of 8.2 ps.     

LiB3O5参量调谐蓝紫光单脉冲皮秒激光器

利用Nd~(3+):YAG主被动锁模加晶体管雪崩吸收单选,再放大、倍频、混频,产生30ps,355nm激光单脉冲,用它泵浦Ⅱ类非临界相应匹配的LiB_3O_5光参量发生器,在精密温度控制下,获得415.9～482.6nm的蓝紫光可调谐输出,线宽0.15nm,最高参量转换效率37.6%,可输出能量为6.33mJ,峰值功率为211MW的皮秒激光单脉冲.     

A picosecond CuBr laser

A novel method for the pulse shortening of the 578 nm spectral line from a CuBr laser is proposed in this paper. By amplifying a seeded picosecond dye laser through the active medium of a CuBr laser, nearly Fourier-transform-limited picosecond pulses of the CuBr laser have been obtained and the output characteristics are also investigated in detail.     

Simple generation of tunable near-infrared picosecond dye-laser pulses using spectro-temporal selection

The spectral and temporal processes in broadband pulsed-laser emissions of near-infrared dyes generated from low-Q and short laser cavities have been investigated with a rate equation model extended to a multiwavelength analysis. A very fast spectral evolution is proved, and this leads to the intrinsic presence of a single short pulse on the short-wavelength wing of the broadband IR dye laser spectrum. From the results, the direct generation of picosecond (≈90 ps)infrared dye-laser pulses adjustable in the 700–850 nm spectral range is successfully demonstrated with spectro-temporal selection, in a compact and simple device, using a nitrogen laser (337.1 nm, 8 ns) or a Q-switched ruby laser (694.3 nm, 25 ns) as a pumping source. Received: 6 October 1998 / Revised version: 14 April 1999 / Published online: 11 August 1999     

Tunable picosecond transient stimulated Raman scattering in ethanol

Transient stimulated Raman scattering (TSRS) of picosecond dye laser pulses in ethanol has been investigated experimentally. In particular some temporal features of TSRS from the C-H stretching mode (2928 cm^-1) in ethanol have been studied with a Photochron II streak camera with subpicosecond time resolution. It is shown that the use of TSRS provides a simple method for producing picosecond pulses tunable over the spectral region ≈492–532 nm and 691–772 nm by tuning a passively mode-locked Rhodamine 6G dye laser from 575–630 nm.     

CVL-pumped dye laser for spectroscopic application

A spectroscopic dye laser system-pumped by a Copper Vapor Laser (CVL)-has been built and optimized for different dye solutions operating in the spectral range from 530 to 890 nm. Conversion efficiencies up to 40% were reached in broad band operation, 24% with a prism expander grating cavity, and 20% in grazing incidence configuration, which operated at typical band widths of 3 GHz. Second harmonic generation (SHG) of the dye laser output produced tunable uv-radiation between 260 and 408 nm at conversion efficiencies 5%. Fundamental and SHG output were used for resonant ionization experiments in molecular beams.     

Generation of short-pulse VUV and XUV radiation

Starting from intense short-pulse KrF (248 nm, 25 mJ, 400 fs), ArF (193 nm, 10 mJ, 1 ps), and Ti:sapphire (810 nm, 100 mJ, 150 fs) laser systems, schemes for the generation of fixed-frequency and tunable VUV and XUV radiation by nonlinear optical techniques are investigated. With the KrF system, a four-wave mixing process in xenon yields tunable radiation in the range of 130–200 nm with output energies of, so far, 100 J in less than 1 ps. For the XUV spectral range below 100 nm, nonperturbative high-order harmonic generation and frequency mixing processes in noble gas jets are considered. To achieve tunability, the intense fixed-frequency pump laser radiation is mixed with less intense but broadly tunable radiation from short-pulse dye lasers or optical parametric generator-amplifier systems. In this way, tunability down to wavelengths of less than 40 nm has been demonstrated.     

Tuning of dye lasers with a reflecting Fizeau wedge

The reflecting properties of the Fizeau interferometer are used to obtain efficient spectral condensation and tuning of short pulse dye lasers. It is pointed out that the formation of multibeam interference fringes with a divergent beam leads to angular dispersion and resurgence of a part of the beam outside the impact area, which can be used to obtain selective feedback in a laser cavity. With a single Fizeau wedge used as a mirror in a 2 ns pulse laser, a linewidth of 0.01 nm is obtained and the tuning range is of the order of 10 nm. The Fizeau wedge mirror also permits an easy switch from a broadband laser emission to a tunable narrow line or to a tunable narrow hole in a broadband laser spectrum.     

Broadly tunable UV-blue picosecond pulsed laser and its application for biological imaging

We have achieved a rapid and random wavelength tuned picosecond pulsed laser and a widely tunable UV-blue picosecond pulsed laser by using the intracavity second harmonic generation of the laser. The tuning range was from 384 to 434 nm with picosecond pulse oscillation. In addition, we demonstrated biological imaging using a fluorescent protein excited by the widely tunable UV-blue picosecond pulsed laser. We found that the laser is suitable for biological imaging using the fluorescent protein as an excitation light source without damages.     

Single picosecond UV pulse generation by mode-locking of an excimer laser-pumped dye laser

A single picosecond ultraviolet pulse has been generated based on mode-locking of a dye laser pumped by a long pulse XeCl laser to serve as the input source for a high-power ps KrF laser system. A short-pulse uv dye laser (BBQ) pumped by an additional XeCl laser was used to selectively amplify a single pulse from a mode-locked pulse train with the pulse separation of 3.2 ns. The amplified single pulse was frequency-doubled to 248 nm with the pulse duration of 20 ps.     

Continuously tunable VUV radiation (129–210 nm) by anti-Stokes Raman scattering in cooled H2

The generation of tunable vacuum ultraviolet radiation by anti-Stokes Raman scattering of tunable ultraviolet dye-laser radiation in cold hydrogen has been investigated. The scattering efficiency of XeCl laser and Nd:YAG laser pumped commercial dye lasers and the influence of different beam profiles has been studied. Up to 12 anti-Stokes orders down to 129 nm were observed with output powers between about 20 kW at =191 nm and somewhat less than 100 W at =129 nm. The efficiency of transversely pumped lasers with an intensity peaked in the center of the beam profile was found to be higher than doughnut shaped intensity distributions. The cooling of the active gas to liquid nitrogen temperatures improved the output pulse energies 3 to 5 times on average. It was found that this intensity increase was caused mainly by the narrowing of the Raman linewidth upon cooling.     

Generation of tunable subnanosecond laser pulses with a nitrogen laser pumped dye laser amplifier system

A simple method for generating single tunable subnanosecond dye laser pulses is described. A Rhodamin 6G dye laser is transversely pumped by a subnanosecond UV pulse of a TEA nitrogen laser. The narrowband output of the dye laser is amplified and shortened in a synchronously pumped amplifier. Narrowband pulses with a duration of 30–40 ps (fwhm) and a pulse power of 30 kW are obtained. They are tunable over the range of 580–600 nm.     

微微秒自动调谐参量激光的研究

采用一对MgO:LiNbO_3角度调谐覆盖了红近外波段0.7～2.2μm,并配以自动波长扫描。文中分析了影响脉冲宽度与线宽的因素,与实验结果相吻合。脉宽<30ps,线宽～1nm(简并波长附近～10nm),单脉冲峰功率达MW级,参量光总能量转换效率达5.4％。