An efficient cavity for optically pumped terahertz lasers

The efficiency of a simply designed cavity for optically pumped pulsed terahertz lasers is studied experimentally. A coated Ge and a crystal quartz act as the input and output windows, respectively. The thickness of the Ge window is designed according to etalon effects to maximize terahertz reflectivity. NH₃ is filled in the cavity as the active medium. When NH₃ is pumped by the 10P(32) line of a TEA CO₂ laser, intense 151.5 μm terahertz radiation is emitted. As high as 19.6 mJ terahertz radiation is extracted from 1.57 J pump energy. The corresponding photon conversion efficiency reaches 35.3%.     

200mJ光泵浦氨气太赫兹激光器北大核心CSCD

利用光栅选支调谐的TEA CO2激光器作为泵浦源设计了高能量脉冲光泵浦太赫兹激光器。太赫兹激光谐振腔由2m长的石英玻璃管、GaAs泵浦光输入窗和SiO2太赫兹光输出窗组成,氨气充入谐振腔内作为增益介质。太赫兹激光的波长由自主设计的金属线栅F-P干涉仪测量。实验中在多个波长处都获得了强烈的太赫兹光输出,其中151.5μm太赫兹光的输出脉冲能量高达204mJ,对应的泵浦光能量为32J。最后,还给出了利用151.5μm太赫兹光进行透视成像的实验结果。     

The tuning characteristics of optically pumped fir cavity laser

Based on the quantum mechanics theory of density matrix and the principle of multiple-beam interference, the tuning characteristics of optically pumped NH₃ FIR lasers were studied. A series of metallic mesh Fabry-Perot cavity lasers with sample tubes of 10cm, 20cm and 100cm in length were constructed and operated successfully, and the FIR laser spectra of the NH₃ cavity lasers pumped by a TEA-CO₂ laser were measured. Supported by the Natural Sciences Foundation of Guangdong Province, PRC     

An optically pumped GaN/AlGaN quantum well intersubband terahertz laser

We propose an optically pumped nonpolar GaN/AlGaN quantum well(QW) active region design for terahertz(THz) lasing in the wavelength range of 30 μm～ 40 μm and operating at room temperature.The fast longitudinal optical(LO) phonon scattering in GaN/AlGaN QWs is used to depopulate the lower laser state,and more importantly,the large LO phonon energy is utilized to reduce the thermal population of the lasing states at high temperatures.The influences of temperature and pump intensity on gain and electron densities are investigated.Based on our simulations,we predict that with a sufficiently high pump intensity,a room temperature operated THz laser using a nonpolar GaN/AlGaN structure is realizable.     

Study of miniature optically pumped NH3 fir cavity laser

A miniature NH₃ molecule FIR cavity laser of 15cm in length pumped by a TEA CO₂ laser was built. The spectral characteristics of the cavity laser and the optimum operating parameters were studied.Supported by the National Natural Sciences Foundation of China     

DCOOD optically pumped by a 13CO2 laser: new terahertz laser lines

In this work we report on new optically pumped THz laser lines from deuterated formic acid (DCOOD). An isotopic ¹³CO₂ laser was used for the first time as a pump source for this molecule, and a Fabry–Perot cavity was used as a THz laser resonator. Optoacoustic absorption spectra were used as a guide to search for new THz laser lines. We could observe six new laser lines in the range from 303.8 μm (0.987 THz) to 725.1 μm (0.413 THz). The lines were characterized according to wavelength, relative polarization, relative intensity, and optimum working pressure. The transferred lamb-dip technique was used to measure the frequency absorption transition for both of these laser lines. Furthermore, we also present a catalogue of all THz laser lines generated from DCOOD.     

Theoretical study of miniature optically pumped cavity NH3 Far-infrared laser

Miniature optically pumped cavity NH3 Far-infrared laser was studied theoretically, with the length of the FIRL cavity as short as 1.5cm, the dependences of FIRL output power and laser lineshape on operating gas pressure and output coupling condition, and on the effect of laser line saturation broadening were calculated.Supported by the National Natural Science Foundation of China.     

Spectra of optically pumped superradiant and cavity NH3 far-infrared laser

Based on the density matrix theory of quantum system, the spectra of optically pumped superradiant and cavity NH₃ far-infrared (FIR) lasers were calculated by means of iteration method. The calculation showed that, compared with the optically pumped superradiant FIR laser, the cavity laser had a wider band spectrum of FIR emission and a higher output power under certain condition, moreover, the spectra of cavity laser had multi longitudinal-mode structure. Supported by the Research Foundation of Hubei Province Education Committee, PRC     

Two-photon optically pumped laser

At high temperature, the transmission peaks of a Fabry-Perot cavity filled with rubidium show sharp structures when the frequency of the laser is close to the 5S_{$\text{1}\text{2}$} - 5D_{$\text{5}\text{2}$} two-photon transition. These structures correspond to a laser emission between 5D_{$\text{5}\text{2}$} and 5P_{$\text{3}\text{2}$}. The wavelength of this laser emission (7759 Å) is smaller than the exciting wavelength (7779 Å).     

A simple carbon dioxide laser amplifier suitable for optically pumped infra-red laser applications

A simple amplifier tube has been designed which, when used with already well-developed, stable single-frequency CO₂ laser oscillators, produces a cw power output of up to 40 W suitable for pumping far infra-red lasers.     

抽运光强度对光学抽运重水气体产生THz激光的影响分析

利用半经典理论，对脉冲光学抽运重水气体产生THz激光信号过程进行分析，对其中抽运光强度与输出THz信号光之间的关系进行了数值计算和求解，结果表明，THz信号出射光强度跟抽运源入射光强度之间不满足简单的线性关系，而是呈现高阶的非线性关系.在工作介质腔长、气压和工作温度一定的条件下，存在最佳抽运光强度，在一定的抽运光强范围内，THz信号出射光强度与抽运源入射光强度的关系呈现近似线性的增长关系，抽运光能量和信号光能量之间的转换效率相对较高，当抽运光强超过一定值时，由于瓶颈效应的发生会导致THz输出信号的逐步减弱，并产生一定的频率调谐范围.     

An optically pumped waveguide laser with mesh reflectors

An optically pumped far infrared waveguide laser has been operated using metallic meshes as laser reflectors. The radiation modes sustained in the waveguide laser have been examined, and the use of the laser for magneto-optical measurements demonstrated.     

Compact extended cavity diode laser system for small optically pumped cesium beam frequency standards

A compact extended cavity diode laser (ECDL) system operating at 852 nm for small optically pumped cesium (Cs) beam frequency standards was reported.ECDL and a saturated absorption spectroscopy setup were all built in an aluminum box with dimension of 10 × 10 × 7 (cm).ECDL was based on a Littman Metcaff configuration,whose free-running linewidth was less than 600 kHz.A digital automatic frequency lock unit (AFLU) was developed to lock the laser frequency to specify Cs absorption lines automatically and re-lock it in case of lock broken.With AFLU,the laser frequency was continuously locked for several weeks.     

High power,high efficiency optically pumped NH3 lasers

A simple and efficient NH₃ laser was tuned over more than 70 vibrational band transitions between 10.08 and 14.14 m. The active medium was a dilute mixture of ammonia in argon and was optically pumped by the 9R(30) transition of a pulsed TEA-CO₂ laser. Output energies greater than 1 J per pulse were observed on several of the strongest lines. In a non-selective cavity an energy conversion efficiency of greater than 35% was obtained with a maximum output energy of 4.6J. Optically pumped NH₃ is shown to be a flexible and efficient system for the downconversion of CO₂ radiation.     

Highly efficient optically pumped cesium vapor laser

We have demonstrated an optically pumped continuous wave Cs vapor laser with an input power to output power slope efficiency of 81%. The laser power was 0.35 W for an input power of 0.57 W, yielding an overall optical efficiency of 63%.     

An optically pumped supersonic iodine beam laser

We report the realisation of an optically pumped I₂-laser using a supersonic beam as active medium. Threshold pump power of the order of 10 mW and output power at λ_d=1.34 μm of up to 2 mW is observed with λ_p=514.5 nm as pump radiation. In contrast to the similar Na₂-beam laser, the output of a ring cavity is bidirectional with a forward to backward intensity ratio of about 10:1.     

A novel cw optically pumped submillimeter laser

Laser operation has been achieved in an optically pumped submillimetre laser that employs a novel cw resonator design which separates the pumping optics from the resonator optics by the use of a Brewster window. This design also allows pumping by an unfocused CO₂ laser beam. The preliminary performance characteristics of the laser are presented.     

Assignments of optically pumped CH3OD laser lines

Fifteen laser lines from CH₃OD pumped by a CO₂ laser are assigned to specific rotational energy transitions. These assignments have been obtained from the approximation that, except for one constant, the molecular constants in the excited CO stretching state are same as those in the ground state.     

Assignments of optically pumped CD3OH laser lines

Six FIR laser lines from CD₃OH pumped by the 10R(36) and the 10R(18) CO₂ laser lines are assigned to specific rotational energy levels in the excited C–0 stretch state. It is found that their upper laser levels are shifted by a Fermi resonance between the C–0 stretch vibration and the third and forth harmonics of the torsional mode. The Fermi resonance shifts are +0.332 cm^–1 and +2.251 cm^–1 for the upper laser levels pumped by the 10R(36) and the 10R(18) CO₂ laser lines, respectively. Calculated frequencies of the pump and the laser transitions agree with those of the pump CO₂ laser lines and the observed FIR laser lines within estimated accuracy.