Tunable,narrow bandwidth, 2 MW dye laser pumped by a KrF1 discharge laser

Characteristics of p-terphenyl and PBD, the most efficient uv dyes, have been investigated under high intensity pumping by a multi-atmosphere KrF¹ discharge laser at 248 nm wavelength. Energy conversion efficiencies, spectral features and temporal behaviour of the dyes were studied parametrically. A maximum powerof 2 MW uv emission with a bandwidth of ～2×10^-2 nm was obtained for PBD. It was found that a mixture of both dyes provided higher (by a factor of 1.3) output in the range 348–366 nm than either of the dyes alone. Significant pump intensity dependent conversion efficiency and pulse shape variations were observed for the most efficient uv dye, p-terphenyl and were related to triplet-triplet adsorption processes in the dye.     

Generation of narrowband tunable VUV radiation at the Lyman-α wavelength

Tunable narrowband VUV radiation has been generated at the Lyman-α wavelength $\text{λ =}\text{1216}\text{\&}\text{A}\text{ring}$; by frequency tripling in krypton the frequency-doubled output of a powerful dye laser system which is excited with the second harmonic of a Nd-YAG laser. 5 ns long UV dye laser pulses ($\text{λ =}\text{3646}\text{A}\text{?}$) of 1.8 MW peak power yielded VUV light pulses of 2.2 W (5.4 × 19⁹ photons/pulse). The bandwidth of the dye laser radiation could be narrowed to 8.7 × 10^-3cm^-1 (4.6 × 10^-3 Å). The expected bandwidth of the VUV is less than 5.2 × 10^-2cm^-1 (7 × 10^-4 Å). The tunable VUV radiation is used for the recording of the absorption spectra of the Lyman-α resonance transitions in atomic hydrogen and deuterium with doppler-limited resolution.     

宽带输出PM580掺杂聚甲基丙烯酸甲酯固体染料激光器研究

采用高效激光染料PM580作为掺杂物质,聚甲基丙烯酸甲酯(PMMA)作为基质,在对固体染料光谱特性研究的基础上,重点研究了调Q倍频Nd:YAG抽运下不同染料掺杂浓度的固体染料激光输出特性.研究结果表明掺杂浓度对输出激光波长影响明显,随着掺杂浓度的增加,激光输出波长红移,从激光增益出发,对该现象给出了理论解释.掺杂浓度对激光转化效率也有影响,当掺杂浓度为2×10^－4mol/L时,获得染料激光输出斜率效率最高达53.8%,抽运能量410mJ时,获得染料激光输出220mJ,激光带宽～8nm 关键词： 固体染料 宽带染料激光 PM580 聚甲基丙烯酸甲酯     

A tunable,frequency-doubled cw dye laser using an RDP crystal

We report a c.w. intracavity, frequency doubled, rhodamine B dye laser using an RDP crystal 5 cm long. Generated uv powers up to 15 mW are obtained in a single direction with a linewidth of 2 GHz over the range 314–318 nm. A conversion efficiency of about 1.25 × 10^-3 W^-1 is measured.     

Some characteristics of efficient dye laser emission obtained by pumping at 248 nm with a high power KrF1 discharge laser

Characteristics of dye laser emission under high intensity uv pumping, at 248 nm wavelength have been investigated with peak pump powers of ～ 10 MW at a pulse duration of ～ 30 ns, provided by a multi-atmosphere KrF¹ discharge laser. Energy conversion efficiencies, spectral features and temporal behaviour of several dyes were parametrically studied. Significant pump intensity dependent conversion efficiency and pulse shape variations were observed for the most efficient uv dye, p-terphenyl.     

LD end-pumped c-Cut Nd:YVO<Subscript>4</Subscript>/KTP self-Raman laser at 560 nm

Intra-cavity sum frequency generation (SFG) of c-cut Nd:YVO₄ self-Raman laser was investigated for the first time. A 4 × 4 × 10 mm³ KTP crystal with a type-II phase-matching cutting angle (θ = 83.4°, φ = 0°) was used for SFG between the fundamental light at 1066 nm and first-Stokes light at 1178 nm. The laser system with different curvature radii of output couplers and different pulse repetition frequencies were investigated. At a pump power of 14 W and pulse repetition frequency of 20 kHz, the average output power of yellow-green laser at 560 nm up to 840 mW was achieved, corresponding to a slope efficiency of 7.6% and a conversion efficiency of 6% with respect to diode pump power.     

消逝波激励的双波段光纤回音壁模式激光辐射

将石英光纤浸入低折射率的染料溶液中后构成圆柱形微腔.采用轴向光抽运消逝波激励激光增益的方式,使增益区域局限在圆柱形微腔回音壁模式的模场区域内,由此显著地提高了抽运效率,增加了沿光纤轴向的增益长度.在一根石英光纤的轴向分段填入浓度同为2×10^-3mol/L的罗丹明6G和罗丹明B乙醇溶液,在567—576nm 和592—600nm的两个波长范围内同时获得回音壁模式的激光辐射;分段填入浓度为8×10^-4和8×10^-3mol/L的罗丹明B乙醇溶液, 关键词： 消逝波激励 圆柱形微腔 回音壁模式 双波段激光辐射     

Spectroscopic characterization and diode-pumped 910 nm laser of Nd:LiLuF4 crystal

Polarized absorption and fluorescence spectra Nd³⁺-doped LiLuF₄ single crystal were investigated. The peak emission cross section at 905 and 910 nm are 0.97 × 10⁻²⁰ and 0.82 × 10⁻²⁰ cm², respectively. Two samples with different dimensions were tested in the laser experiments. With a laser-diode as the pump source, a maximum 1.17 W laser output at 910 nm has been obtained with a slope efficiency of 16.3% with respect to the pump power.     

Co-axially pumped,narrow band,continuously tunable,high power VUV xenon laser

High efficiency spectral narrowing to 0.13 nm and frequency tuning from 169 nm to 176 nm has been produced with a new design of coaxial-pumped xenon laser employing a single intra-cavity prism. The laser peak power is 3 MW (9 mJ) and becomes 0.7 MW (power density 10 MW cm^-2) when frequency narrowed.     

Turnable Second Harmonic Generation from an Organic Dye Laser

Abstract

Ultraviolet light has been generated from a Rhodamine 60 organic dye laser by frequency doubling with a KDP crystal. The second harmonic was tuned from 2900Å to 3000Å with peak powers of 40 watts.

Organic dye lasers have now been reported with output wave-lengths extending throughout the visible and near infrared^1-12. The tunability^4,6,13 and output energies now available in the visible protion of the spectrum suggest frequency doubling as a means of obtaining a tunable source of ultraviolet light. We wish to report the observation of tunable second harmonic radiation centered at 2950Å generated from the laser output of a 10^?4 molar solution of Rhodamine 6G dissolved in ethyl alcohol.     

A coherent light source,widely tunable down to 16 μm by stimulated Raman scattering

An infra-red emission tunable down to 16 μm is produced by a hydrogen Stokes shifted dye laser. The peak power measured at 16 μm is of ca. 50 kW in 2 ns within a one millimeter diameter beam. The corresponding light flux of the order of 5 MW cm^-2 could allow a multi-step vibrational excitation of molecules absorbing down to 16 μm. Simultaneous emissions from the laser and from the previous Stokes bands are available at: 0.76, 1.62, 2.09 μm with respective peak powers of 550, 50 and 20 MW. Spectral widths of 0.8 cm^-1 and of ca. 7 × 10^-2 cm^-1 are obtained for the dye laser and for each of the Stokes band respectively.     

Frequency stabilization of a single-frequency volume Bragg grating-based short-cavity Tm:Ho:YLF laser to a CO2 line at 2.06?μm

This study presents a 2.06???m single-frequency tunable volume Bragg grating (VBG)-based short-cavity Tm:Ho:YLF laser. A mode-hop-free tuning range of 10?GHz at a few hundred mW output power was achieved. The first-derivative spectrum of the CO₂ 20013??00001 R(4) absorption line with a signal-to-noise ratio (SNR) of 1,000/Hz^1/2 was obtained using frequency modulation and fluorescence detection. The laser frequency can be stabilized to the CO₂ line with a stability of 3?×?10^?9.     

Laser dye stability

Lasing characteristics and bleaching of four Eastman Kodak ir dyes have been examined in dimethyl sulfoxide. These ir dyes are shown to improve in performance in the absence of oxygen. Their photochemical stability was found to be comparable to the quinolone laser dyes when exposed to flashlamp excitation. Photodecomposition of the ir dyes under lasing conditions was found to vary between 1.6 and 6×10⁻¹⁰ moles of dye for each joule (electrical) of input energy; in comparison, the photodecomposition values for the better coumarin dyes was 0.2 to 1.0×10⁻¹⁰ moles/J at a concentration of 1.0×10⁻⁴ M in ethanol. It was also found that increasing the concentration of these tricarbocyanine dyes gives a marked improvement in the useful lifetime of these solutions as lasing media in the absence of oxygen.     

在BBO中获得230.8—223.2nm高功率和频输出

用Q-YAG泵浦的Rh·6G染料激光在一块45°切割的β-BaB₂O₄(BBO)晶体中倍频,产生294.8—282.5nm范围的连续调谐输出,其能量为8mJ(在285nm处)。用这个倍频光与泵浦染料后剩余基波(1064nm)在另一块45°切割的BBO中和频,已获得230.8—223.2nm范围的连续调谐输出,其能量为120μJ,相应的峰值功率为12kW。还简述了获得高功率和频输出的关键技术。     

Tunable XUV radiation generated by nonresonant frequency tripling in argon

Nonresonant frequency tripling of the ultraviolet (UV) radiation of a frequency doubled pulsed dye laser generates in argon coherent radiation in the extreme ultraviolet (XUV). The radiation is tunable in spectral regions of negative dispersion λ_XUV = 97.4–104.75 nm, λ_XUV = 86.8–86.98 nm and λ_XUV = 85.7–86.68 nm located at the high energy side of the transitions 3p-4s′ [$\text{1}\text{2}$,1], 3p-5s′ [$\text{1}\text{2}$,1] and 3p-3d′ [$\text{3}\text{2}$,1], respectively. At UV input pulse powers of 1–2 MW the pr oduced. XUV power was typically 1–8 W (0.2–1.6 × 10¹⁰ photons/pulse).     

Solid-state dye lasers based on polymethyl methacrylate doped with pyrromethene 650

Solid-state dye samples based on polymethyl methacrylate (PMMA) doped with different concentrations of the dye PM650 were prepared. With SHG of Q-switched Nd:YAG laser (532 nm, ∼15 ns) pumping the samples longitudinally, the fluorescence, lasing spectra and slope efficiencies of the samples were obtained. The highest slope efficiency 27.49% and laser output energy 22.0 mJ was achieved in the sample with a dye concentration of 2.0 × 10⁻⁴ mol/L. To our knowledge, the results are the best under the same condition so far. The maxima of output lasing spectrum is about 653.5 nm. Our results have shown that using solid-state samples doped with PM650 can extend the dye laser wavelength to the red.     

A New Candidate Laser Dye Based 1,4-Bis[β-(2-Naphthothiazolyle)Vinyl]Benzene. Spectroscopic Behavior,Laser Parameters and Excitation Energy Transfer

A new candidate laser dye based 1,4-bis[β-(2-naphthothisolyl) vinyl] benzene (BNTVB) were prepared, and characterized in various organic solvents. The center polarity is less sensitive than electronic absorption. A red shift was noticed in the fluorescence spectra (ca. 40 nm) with increment in the solvent’s polarity, this means that BNTVB’s polarity appreciates upon excitation. The dipole moment of ground state (μ_g) and the excited singlet state dipole moment (μ_e) are determined from Kawski – Chamma and Bakshiev–Viallet equations using the disparity of Stokes shift with solvent polarity function of ε (dielectric constant) and n (refractive index) of the solvent. The result was found to be 0.019D and 5.13D for ground and exited state, in succession. DFT/TD-DFT manners were used to understand the electronic structures and geometric of BNTVB in other solvents. The experimental and theoretical results showed a good agreement. The photochemical quantum yield (Ф_c) of BNTVB was calculated in variable organic reagents such as Dioxane, CHCl₃, EtOH and MeOH at room temperature. The values of φ_c were calculated as 2.3?×?10^?4, 3.3?×?10^?3, 9.7?×?10^?5 and 6.2?×?10^?5 in Dioxane, CHCl₃, EtOH and MeOH, respectively. The dye solutions (2?×?10^?4 M) in DMF, MeOH and EtOH give laser emission in the blue-green region. The green zone is excited by nitrogen pulse 337.1 nm. The tuning range, gain coefficient (α) and cross – section emission (σ_e) of laser were also estimated. Excitation energy transfer from BNTVB to rhodamine-6G (R6G) and N,N-bis(2,6-dimethyphenyl)-3,4:9,10-perylenebis-(dicarboximide) (BDP) was also studied in EtOH to increase the laser emission output from R6G and BDP when excited by nitrogen laser. The dye-transfer power laser system (ETDL) obeys the Foster Power Transmission (FERT) mechanism with a critical transmission distance, R_o of 40 and 32 ? and k_ET equals 2.6?×?10¹³ and 1.06?×?10¹³ M^?1 s^?1 for BNTVB / R6G and BNTVB / BDP pair, respectively.     

Single-longitudinal mode, monolithic, green solid-state laser

We present the practical realization of a monolithic single-frequency diode pumped Nd:YVO₄/YVO₄/KTP microchip laser with birefringent filter operating at 532?nm. Theoretical analysis of the single-mode operation of such a laser configuration is presented. Experimental results are in good agreement with theoretical analysis. The laser operated with output power up to 90?mW at 532?nm. The total optical efficiency (808?nm to 532?nm) was 9.5%. Power stability was at the level of ±0.75% and the long-term frequency stability was approximately 3×10^?8. The beam has a Gaussian profile and the M2 parameter was below 1.2.     

Near IR laser light visualizators using nonlinear GaSe and other layered crystallites

Two methods of preparation of the devices for visualization of pulsed and continuous near-IR (near infrared) are described and the results of conversion of pulsed and continuous IR (800–1360 nm) laser radiation into the visible range of spectra (400–680 nm) by using a transparent substrate covered with the particles (including nanoparticles) of effective nonlinear materials of GaSe _x S_{1 − x} (0.2 ≤ x ≤ 0.8) are presented. Converted light can be detected in transmission or reflection geometry as a visible spot corresponding to the real size of the incident laser beam. Developed device structures can be used for checking if the laser is working or not, for optical adjustment, for visualization of distribution of laser radiation over the cross of the beam and for investigation of the content of the laser radiation. Low energy (power density) limit for visualization of the IR laser pulses with 2–3 ps duration for these device structures are: between 4.6–2.1 μJ (3 × 10⁻⁴−1 × 10⁻⁴ W/cm²) at 1200 nm; between 8.4–2.6 μJ (4.7 × 10⁻⁴−1.5 × 10⁻⁴ W/cm²) at 1300 nm; between 14.4–8.1 μJ (8.2 × 10⁻⁴–4.6 × 10⁻⁴ W/cm²) at 1360 nm. Threshold damage density is more than 10 MW/cm² at λ = 1060 nm, pulse duration τ = 35 ps. The results are compared with commercially existing laser light visualizators.     

Nd:YVO4自受激拉曼激光器调Q锁模特性

利用Nd:YVO4激光晶体的自受激拉曼效应,结合Cr:YAG被动锁模技术和倍频技术,实现了结构紧凑的1176 nm和588 nm黄光锁模激光输出。激光器为LD端面泵浦,三镜折叠腔结构,并且采用了透过率为10%的输出镜。Nd:YVO4晶体长度为10 mm,Nd3+离子掺杂质量分数为0.2%,Cr:YAG晶体的初始透过率为67%。10 W激光泵浦时,1176 nm激光平均输出功率为123 mW,调Q包络宽度为6 ns,调Q包络内的锁模脉冲重复频率高达1 GHz。588.2 nm 黄光的平均输出功率为8 mW。