High-power,line-tunable14NH3 and15NH3 lasers

A high-power, line-tunable NH₃ laser pumped by a TEA CO₂ laser has been developed for application to laser isotope separation of tritium. Laser lines from¹⁵NH₃ are newly observed in a range from 11.24 to 13.23 m. The performance of an¹⁵NH₃ laser is compared to that of an¹⁴NH₃ laser.     

New FIR laser lines from an optically pumped far-infrared laser with isotopic 13C16O2 pumping

A ¹³C¹⁶O₂ laser optically pumping a FIR laser has resulted in 17 new FIR cw emissions from 78.5 μm to 917 μm. The FIR media were: CD₃OD, CH₃OD, CD₃OH, NH₃ and ¹⁵NH₃. Interesting effects have been observed with a combination of NH₃ and CD₃OD resulting in a new FIR emission. Two new FIR emissions at 181.5 μm and 355.5 μm have been observed with a ¹²C¹⁶O₂ laser optically pumping CD₃OD.     

Diode-pumped monolithic Er3+:Yb3+:YAl3(BO3)4 micro-laser at 1.6 μm

Efficient eye-safe 1.6 μm monolithic laser was realized in a c-cut, 0.7-mm-thick Er³⁺:Yb³⁺:YAl₃(BO₃)₄ microchip end-pumped by a quasi-continuous-wave 970 nm diode laser. At incident pump peak power of 20.4 W, a maximum output peak power of 2.6 W with a slope efficiency of 19% was obtained when the waist radius of pump laser beam was 220 μm. The spectra and profiles of output beam of the Er³⁺:Yb³⁺:YAl₃(BO₃)₄ monolithic laser were measured. The influences of the waist radius of pump laser beam on the slope efficiency and threshold of the monolithic laser were also investigated.     

Experimental study of nuclear processes in the presence of superstrong fields of a picosecond laser plasma

Nuclear processes in the presence of the superstrong laser fields of a picosecond laser plasma are experimentally studied at a radiation intensity of 2 × 10¹⁸ W/cm² on a Neodim laser setup with a power of 10 TW. Experimental data regarding neutron generation on the surface of a deuterated target (CD₂)_n owing to the thermonuclear fusion ²H(d,n)³He and the neutron generation on the Be target due to the photonuclear reaction ⁹Be(γ,n)2α are presented. Neutron yields Y _n of 10⁶ and 10³ per 4π sr per laser pulse are obtained for the (CD₂)_n and Be targets, respectively. The alpha-particle yield is measured for the first time in the neutron-free thermonuclear reactions ¹¹B + H → 3⁴He in the laser plasma on the surface of the composite B + (CH₂)_n targets. The alpha-particle yield is 10³ per 4π sr per laser pulse.     

Atomic mercury photodissociation laser in the visible

Stimulated emission on two new pulsed laser lines in atomic mercury is reported. The laser emits at 435.8 and 546.1 nm, corresponding to the transitions 7 ³S₁ → 6 ³P₁ and 7 ³S₁ → 6 ³P₀ of the neutral atomic mercury atom. Population inversion is generated by photodissociation of HgI₂ vapor with a KrF laser at 248 nm. 150mJ of KrF laser radiation were focused into the HgI₂ cell by means of a cylindrical lens in a transverse pumping configuration. With a single end mirror pulses with a peak power of 3 kW and duration of approximately 1 ns were generated. The pumping mechanism is proposed to be a sequential three-photon process.     

Measurement and assignment of new FIR laser lines in12CH3OH and13CH3OH

We have found twelve new FIR laser lines in¹²CH₃OH and thirty three in¹³CH₃OH. Both molecules were pumped by a regular cw CO₂ laser. We have also assigned 20¹³CH₃OH laser lines to specific rotational energy levels in the excited C-O stretchhindered rotation combined states     

Transversely pumped laser using F 3 + and F2 mixed color centers in a LiF crystal at room temperature

A stable laser with F₃⁺ and F₂ mixed color centers in LiF crystal is constructed using a transversely pumped cavity at room temperature. The mixed color center laser is pumped with a nitrogen-laser-pumped dye laser. A pulse output of the laser is 0.23 mJ. The pulse widths of the F₃⁺ and F₂ color center lasers are about 12 and 8.5 ns, respectively. The optical–optical conversion efficiency is about 5.0%. The divergence of the F₃⁺ color center laser beam is about 2.2 mrad and that of the F₂ color center laser beam about 3.5 mrad. The polarization of the mixed color center laser is about 0.97. The output of the F₃⁺ color center laser extends from 515 to 575 nm and peaks at 540 nm, while that of the F₂ color center laser extends from 633 to 705 nm and peaks at 667 nm.     

New cw two-photon pumped and Raman fir laser lines in 14NH3 and 15NH3

Application of infrared-microwave two-photon pumping on ¹⁴NH₃ and ¹⁵NH₃ yields 17 new cw laser lines in the far infrared. In addition a new Raman laser line in ¹⁵NH₃ is found.     

Discovery and frequency measurement of short-wavelength far-infrared laser emissions from optically pumped <Superscript>13</Superscript>CD<Subscript>3</Subscript>OH and CHD<Subscript>2</Subscript>OH

A three-laser heterodyne system was used to measure the frequencies of twelve previously observed far-infrared laser emissions from the partially deuterated methanol isotopologues ¹³CD₃OH and CHD₂OH. Two laser emissions, a 53.773 μm line from ¹³CD₃OH and a 74.939 μm line from CHD₂OH, have also been discovered and frequency measured. The CO₂ pump laser offset frequency was measured with respect to its center frequency for twenty-four FIR laser emissions from CH₃OH, ¹³CD₃OH and CHD₂OH. PACS 07.57.Hm; 42.55.Lt; 42.62.Eh     

12CH3OH and 13CH3OH optically pumped by the 10P and 10HP bands of a pulsed CO2 laser: New far-infrared laser emissions and assignments

We have re-investigated the ¹²CH₃OH and the ¹³CH₃OH molecules as optically pumped far-infrared laser sources. We have used our new waveguide pulsed-high-peak-power CO₂ laser for pumping, finding 20 new far-infrared laser lines emitted by ¹²CH₃OH and seven emitted by ¹³CH₃OH. For each line we report wavelength, pump offset from the center of the exciting CO₂ line, relative polarization, optimum operating pressure and intensity. The LaseRitz program was able to assign one of the new laser systems of ¹²CH₃OH, involving two new far-infrared laser lines.PACS 42.55.Lt; 42.62.Fi     

Observation of photon echoes using a nitrogen laser pumped dye laser

Photon echoes have been observed using a nitrogen laser pumped dye laser as the excitation source. The echo was obtained in the ³H₄→³P₀ transition in Pr³⁺:LaF₃. The dependence of echoes on magnetic field and temperature was measured.     

A miniature tunable TEA CO<Subscript>2</Subscript> laser using isotope <Superscript>13</Superscript>C<Superscript>16</Superscript>O<Subscript>2</Subscript> and <Superscript>12</Superscript>C<Superscript>16</Superscript>O<Subscript>2</Subscript>

A miniature tunable TEA CO₂ laser using isotope ¹³C¹⁶O₂ as the active medium is developed to extend the spectral range of CO₂ lasers for further application. The optimization of the energy parameters of the tunable TEA ¹³C¹⁶O₂ laser and the same laser using ¹²C¹⁶O₂ are studied. When a gas mixture (¹³C¹⁶O₂: N₂: He = 1: 1: 3) at a total pressure of 6.4 × 10⁴ Pa is used, the TEA ¹³C¹⁶O₂ laser of a 45-cm³ active volume obtains 51 emission lines in the [00⁰1–10⁰0] and [00⁰1–02⁰0] bands. The maximum pulse energy of the TEA ¹³C¹⁶O₂ laser is about 357 mJ. The same laser using the conventional gas mixture (¹²C¹⁶O₂: N₂: He = 1: 1: 3) at a pressure of 6.66 × 10⁴ Pa is measured to obtain 69 laser emission lines and the maximum pulse energy of laser radiation is about 409 mJ.     

用于准相位匹配的LD泵浦Nd:YAG946nm连续激光光源

本文为泵浦质子交换准相位匹配波导器LiNbO₃提供了激光光源,用808nm半导体激光器泵浦Nd:YAG晶体,在室温下获得946nm激光连续输出大于120mW,斜率效率9.8%,并且在国内首次实现了LD泵浦Nd:YAG/KNbO₃473nm蓝色激光器的连续运转,报道了初步的实验结果并对此进行了详细的分析,提出了改进方案.     

Self-induced transparency in Pr3+:LaF3

Observation of self-induced transparency for the ³H₄ → ³P₀ transition of Pr³⁺:LaF₃ is reported. Pulse delays, reshaping and breakup were obtained using a pulsed nitrogen laser pumped dye laser for resonant excitation.     

New all-solid-state tunable UV Ce3+, Yb3+:LiY0.4Lu0.6F4 laser

Here we report laser test results of the new UV solid-state active medium based on a Ce³⁺, Yb³⁺:LiY_0.4Lu_0.6F₄ mixed crystal pumped by radiation from Ce:LiCAF laser. The 10-Hz pulse repetition rate Ce³⁺, Yb³⁺:LiY_0.4Lu_0.6F₄ laser yielded a maximum output power of 0.25 mJ at 311nm in non-optimized non-selective resonator with a maximal slope efficiency of 13%. Tunability from 304 to 332 nm was achieved in the selective single-prism resonator.     

The rotation-vibration constants of the 12CH3F ν3 band

Accurate rotational and vibrational constants for the ground and the ν₃ states of ¹²CH₃F are derived from a simultaneous least-squares fit of all the previous microwave, laser Stark and far-infrared laser data related to the ν₃ ← 0 band. Spectroscopic data, concerning the far-infrared laser emission in ¹²CH₃F, are discussed.     

Laser Lines and Frequency Measurements of Fully Deuterated Isotopomers of Methanol

Fully deuterated isotopomers of methanol (¹²CD₃OD and ¹³CD₃OD) were optically pumped with a CO₂ laser. Five new far-infrared laser lines were discovered in ¹²CD₃OD and 25 in ¹³CD₃OD in the range 43.697 to 719.426 m. The frequencies of these new and some previously reported laser lines, the pump offset, the relative polarization, the relative intensity, and the optimum pressure of operation were measured.     

Far infrared laser lines produced by methanol and its isotopic species: A review

Methanol (CH₃OH) is considered today one of the most important active media for the generation of laser radiation in the far-infrared (FIR) spectral region. Together with ten of its other isotopic species, it is responsible for the major part of the laser lines generated by the optical pumping technique. Due to the extreme importance of those molecules as laser generators, we understood that there was a necessity of a comprehensive work which would include as much pratical information as possible about each line.Chang et al⁽¹⁾ early recognized methanol as a source of strong FIR laser lines. Since then, more than 100 papers were published containing information about new laser emission. Recently, Moruzzi et al⁽¹¹⁴⁾ presented a review of 575 lines produced by¹²CH₃OH. In the present paper, we have extended the review to the various isotopic modifications of this molecule (namely¹³CH₃OH, CD₃OH,¹³CD₃OH, CD₃OD,¹³CD₃OD, CH₃OD, CH ₃ ¹⁸ OH, CH₂DOH, CH₂DOD and CHD₂OH), a total of nearly 2000 lines with wavelengths ranging from 19µm to 3030µm.     

A review of optically pumped far-infrared laser lines from methanol isotopes

The technique of optical pumping in polar molecules is the most efficient for Far-Infrared (FIR) laser generation, providing also a versatile and powerful tool for molecular spectroscopy in this spectral region. Methanol (CH₃OH) and its isotopic varieties are the best media for optically pumped FIR laser, with over thousand lines observed, and the most widely used for investigations and applications. In this sense, it is important organize and make available catalogues of FIR laser lines as complete as possible. Since the last critical reviews of 1984 [1] on methanol and its isotopic varieties [2,3,4], over hundred papers have been published dealing with hundreds of new FIR laser lines. In 1992 a review of FIR laser lines from CH₃OH was presented [5]. In this communication we extend this work to the other methanol isotopes, namely CH₃OD, CD₃OH, CD₃OD,¹³CH₃OH,¹³CD₃OH,¹³CD₃OD, CH₃ ¹⁸OH, CH₂DOH, CHD₂OH and CH₂DOD.Work supported by FAPESP, CNPq, FAEP-Brasil, and CNR-Italia     

650-nm laser emission under upconversion pumping at 1.064 μm in Tm<Superscript>+3</Superscript>: ZBLAN fiber laser

We report for the first time continuous wave (CW) red laser emission in Tm⁺³-doped ZBLAN fiber laser, operated at 650 nm (¹ G ₄ → ³ F ₄ transition of Tm⁺³). The excitation uses a three step upconversion scheme. The pump source is a Nd:YAG laser operated at 1.064 μm. A laser output power of CW 80 mW was obtained for 1.42 W of launched pump power. The slope efficiency with respect to launched pump power was measured to be 7.7%. The temporal behavior of the emitted laser is also addressed.