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Highly doped erbium crystals have complex fine energy levels, which can be used to emit lasers of different wavelengths under different conditions. The mid-infrared multi-wavelength laser of erbium ions has not yet achieved stable laser emission. In this study, the rate equation is used, with consideration of mode competition, to design a mid-infrared Er:YAG pulsed laser that emits four wavelengths at room temperature. The gain of the multi-wavelength erbium laser is related to the Boltzmann distribution coefficient. Based on this, the conditions for multi-wavelength output have been calculated and verified in experiments. A four-wavelength stable output mid-infrared pulsed laser based on Er:YAG was produced. This laser may be applied to remote sensing or gas detection.

Recently, the optically pumped rare gas lasers have been attracted extensive attention. Rare gas laser systems with Ne (2p 5 3p), Ar (3p 5 4p), and Kr (4p 5 5p) atoms have been investigated. However, there are sparse studies based on Xe. In this work, new phenomena, intensive mid-infrared amplified spontaneous emissions (ASEs), are found after two-photon excitation of Xe from the ground state to the 6p[1/2] 0 state. Simultaneously, substantial 6p[1/2] 1 atoms are populated. The thresholds of ASE peak 1 and the generation of 6p[1/2] 1 atoms are both about 1.5 mJ. It indicates that there should exist the relationship between these two phenomena. The ASE signals show broadband spectra. Therefore, it must be yielded by the superposition of Xe 2 * excimer transitions. The mid-infrared ASEs lead to excimers correlating to the 6s’[1/2] 1 enormously generated. Then these excimers dissociate to produce substantial 6p[1/2] 1 atoms. Under some circumstance, the ratio of the 6p[1/2] 1 to 6p[1/2] 0 atoms reaches about 80%. It indicates that the 6p[1/2] 0 atoms strongly tend to decay through the emissions between the excimer states. Using these emissions, continuous-tunable mid-infrared laser with metastable Xe can be promisingly produced.

Combustion parametric optimization for all gas-phase iodine laser driven by D(2)/NF(3)/DCl combustion was performed, and an energy transfer channel called self-pooling of NCl(a) catalyzed by NF(a)/NF(b) was presented. The results show that a flow rate ratio of NF(3) and D(2) of 0.8 to 1.5 and DCl and D(2) of1.5 is necessary for high efficiency of Cl atoms generation. The results also show that NF(a) and NF(b) from the reaction of HN(3) and residual F atoms or from the D(2)/NF(3) combustion have a serious effect on the generation and transport of NCl(a) via the NF(a) direct quenching of NCl(a) or via the catalysis of NF(a)/NF(b) on NCl(a) self-pooling. The generation of NF can be avoided if sufficient DCl was used and the NF(3)/D(2) flow rate ratio was properly controlled.

High press, gravity-independent, singlet oxygen generator (HGSOG) [1] with small reaction zone and high chemical efficiency was designed and fabricated. The mixing, reaction and separation processes happened simultaneously in the reaction zone of HGSOG. The size and the configuration of reaction zone are very important for HGSOG. In this paper, p-τ value was calculated to determine the upper limit of the volume of reaction zone. The condition of gas-liquid separation was calculated to determine the lower limit of the volume of reaction zone. The utilization rate of Cl 2 achieved 90% and the yield of O 2 ( 1 Δ) reached 70%.

Two electrochemical methods for regeneration of Basic Hydrogen Peroxide (BHP) were investigated in this paper, which could be called one-step method and two-step method, respectively, distinguished by the number of steps during the regeneration process. The one-step method converts potassi um chloride solution and oxygen directly to chlorine and BHP by a modified chlor-alkali cell with an oxygen cathode. For the one-step met hod, two reactors of different structure and corresponding regenerating process were designed. The experimental results showed that, for the continuous-type reactor, the highest peroxide concentration was 0.042 mol/L, while for batch-type reactor the highest peroxide concentration was 0.563 mol/L. The two-step method accomplishes the regeneration of BHP by a conventional chlor-alkali cell combined with a fuel cell reactor which could convert hydrogen and oxygen to peroxide in alkaline potassium hydroxide solution. A peroxide concentration of 2.450 mol/L was obtained for the two-step method. Basic hydrogen peroxide; Electrochemical regeneration; Chemical Oxygen-Iodine Laser

A dual-components absorption method based on absorption spectroscopy was described in the paper. It can easily eliminate the influence of the serious contamination and aerosol scattering on IFR measurement by utilizing the absorptions of iodine vapor and chlorine on two different wavelengths respectively. According to the character that there is no other gaseous product in the reaction besides iodine vapor, IFR in real time can be obtained by the connections of the pressure and the flow rate among chlorine remainder, iodine vapor, and the buffer gas. We used this method to measure IFR for the first time at the exit of a chemical iodine generator. The average of IFR is coincident with that calculated by chemical weighting mass.

Singlet oxygen generator (SOG) is the key part of chemical oxygen iodine laser (COIL) which supplies chemical energy for chemical oxygen iodine laser. A novel pre-swirling jet singlet oxygen generator (PJSOG) with rapid separation technology is put forward. In this paper, experimental performances of PJSOG have been studied by means of theoretical and experimental analysis. With excellent phase dispersion and rapid separation performances, PJSOG has several or several decade times specific area than traditional SOGs and high separation efficiency. It can reach more than 95% chlorine utilization and about 60% O 2 ( 1 u yield. The operating stability has also been studied in this paper. The stablerunning time of PJSOG increased with liquid flow structure improvement. With high separation efficiency, high O 2 ( 1 u output coefficient, high utilization coefficient of Cl 2 and excellent operating stability, the novel PJSOG must be a pr omising technology in further research. singlet oxygen generator; phase dispersion; separation; operating stability

A traditional pressure recovery system is the major obstacle to mobile chemical oxygen-iodine laser (COIL) for its huge volume. A cryosorption vacuum pump was used as the pressure recovery system for different buffer gases. It made COIL become a flexible, quiet and pressure-tight. Experiments were carried out on a verti- COIL, which was designed for N 2 and energized by a square-pipe jet singlet oxygen generator (JSOG). The output power with CO 2 was 27.3% lower than that with N 2 , but the zeolite bed showed an adsorption capacity threefold higher for CO 2 than for N 2 in the continuous operation. The great volume efficiency interested researchers.

Achieving population inversion through multi-photon cascade pumping is almost always difficult, and most laser medium work under 1-photon excitation mechanism. But for alkali atoms such as cesium, relatively large absorption cross sections of several low, cascading energy levels enable them properties such as up conversion. Here we carried out research on two-photon excitation alkali fluorescence. Two photons of near infrared region are used to excite alkali atoms to n 2 D 5/2 , n 2 D 3/2 or higher energy levels, then the blue fluorescence of (n+1) 2 P 3/2 ,(n+1) 2 P 1/2 →n 2 S 1/2 are observed. Different pumping paths are tried and by the recorded spectra, transition routes of cesium are deducted and concluded. Finally the possibility of two-photon style DPALs (diode pumped alkali laser) are discussed, such alkali lasers can give output wavelengths in the shorter end of visual spectroscopy (400-460 nm) and are expected to get application in underwater communication and material laser processing.

A chemical oxygen-iodine laser (COIL) is an electronic transition, low pressure, high throughput system. The use of this laser demands a suitable pressure recovery system. This paper proposed a novel pressure recovery system based on chemical absorption and the feasibility for COIL with CO 2 as buffer gas (CO 2 -COIL) was investigated. The novel pressure recovery system works by chemisorbing the CO 2 -COIL effluents into two fixed-beds maintained at initial temperature of around 293-323K. Compared with the cryosorption system for N 2 -COIL based on physical absorption, the novel chemisorptions based pressure recovery system has a simpler logistics and a shorter run-to-run preparation time. Two kinds of solid chemo-sorbents were designed and synthesized. One was used for chemisorbing the oxidizing gases such as O 2 ,Cl 2 and I 2 , another was used for chemisorbing the acidic gas such as CO 2 . The capacities of the two sorbents were measured to be 3.12 mmol（O 2 ）/g and 3.84 mmol (CO 2 ) /g, respectively. It indicated that the synthesized sorbents could effectively chemosorb the CO 2 -COIL effluents. Secondly, analog test equipment was set up and used to study the feasibility of the novel pressure recovery system used for CO 2 -COIL. The test results showed that the novel pressure recovery system could maintain the pressure under 6 Torr for tens seconds under the continuous gas flow. It showed that the novel pressure recovery system for CO 2 -COIL based on chemical absorption is feasible.

Sodium based excimer-pump alkali laser (Na-XPAL) is expected to be an efficient method to generate sodium beacon light, but the information about the spectroscopic characters of Na-XPAL remains sparse so far. In this work, we utilized the relative fluorescence intensity to study the absorption spectrum of blue satellites of complexes of sodium with different collision partners. The yellow fluorescence of Na D 1 and D 2 line was clearly visible. After processing the fluorescence intensity and the input pumping laser relative intensity, we obtained the Na-CH 4 system’s blue satellites was from 553nm to 556nm. Meanwhile, we experimentally demonstrated the Na-Ar and Na-Xe system’s wavelength range of blue satellites. Also, it was observed that the Na-Xe system’s absorption was stronger than the other two systems.

Separation performance of a new spray-type singlet oxygen generator (SOG), named strongly swirling flow singlet oxygen generator (SSF-SOG), is studied by computational fluid dynamics (CFD) analysis and experiments. The flow field and the separation performance of the SSF-SOG are analyzed using Fluent® soft firstly, and the results show that the separation performance of SSF-SOG is effective for liquid droplets whose diameters are greater than 5μm. Then, using Phase Doppler Particle Analyzer (PDPA), the diameters of liquid droplets in reaction zone and gas outlet of SSF-SOG are measured. The results show that in the reaction zone the diameters of the liquid droplets mainly concentrated on 10μm, and only a little of droplets of which the diameter are under 5μm are detected in the gas outlet of SSF-SOG, which are well consistent with the results of the CFD analysis on SSF-SOG.

A 2-kW-class chemical oxygen-iodine laser (COIL) using nitrogen buffer gas has been developed and tested since industrial applications of COIL devices will require the use of nitrogen as the buffer gas. The laser, with a gain length of 11.7 cm, is energized by a square pipe-array jet-type singlet oxygen generator (SPJSOG) and employs a nozzle bank with a designed Mach number of 2.5. The SPJSOG has advantages over the traditional plate-type JSOG in that it has less requirements on basic hydrogen peroxide (BHP) pump, and more important, it has much better operational stability. The SPJSOG without a cold trap and a gas-liquid separator could provide reliable operations for a total gas flow rate up to 450 mmol/s and with a low liquid driving pressure of around 0.7 atm or even lower. The nozzle bank was specially designed for a COIL using nitrogen as the buffer gas. The cavity was designed for a Mach number of 2.5, in order to provide a gas speed and static temperature in the cavity similar to that for a traditional COIL with helium buffer gas and a Mach 2 nozzle. An output power of 2.6 kW was obtained for a chlorine flow rate of 140 mmol/s, corresponding to a chemical efficiency of 20.4%. When the chlorine flow rate was reduced to 115 mmol/s, a higher chemical efficiency of 22.7% was attained. Measurements showed that the SPJSOG during normal operation could provide a singlet oxygen yield Y/spl ges/55%, a chlorine utilization U/spl ges/85%, and a relative water vapor concentration w=[H/sub 2/O]/([O/sub 2/]+[Cl/sub 2/])/spl les/0.1.

By means of a microwave generator, chlorine diluted by helium was dissociated to chlorine atoms that subsequently reacted with hydrogen azide to produce the excited states of NCl(a 1 Δ) and NCl(b 1 Σ). In this paper, the intensity of NCl(a 1 Δ) and NCl(b 1 Σ) emission dependent on the flow rates of different gases was studied. Moreover, the production of NCl(a 1 Δ) and NCl(b 1 Σ) along the reaction tube was also investigated. The results are presented and discussed. The optimum parameters for NCl(a 1 Δ) and NCl(b 1 Σ) production are given, and the quenching rate of NCl(a 1 Δ) by Cl 2 is obtained.

Sodium-ethane excimer pairs are studied and proved to be a great choice of excimer pumped sodium laser (XPNaL) gain media. The lifetime of the sodium D2 line is studied in a sodium-ethane excimer system excited by a 553 nm laser, and the observed phenomenon of lifetime lengthening is discussed. Amplified spontaneous emission (ASE) of the sodium D2 line is successfully obtained, and its time-resolved and spectroscopic characteristics are studied experimentally. According to the intensity of the ASE signal under different sodium vapor atom densities, the sodium D2 line gain feature of sodium-ethane excimer pairs excited by the 553 nm laser is concluded.

A supersonic all gas-phase iodine laser driven by NF 3 /D 2 /DCl/CF 3 I combustion has been experimentally studied. the gain signals of I( 2 P 3/2, F=4)← I( 2 P 1/2 ,F=3) at 1315.246nm and I( 2 P 3/2 ,F=3)← I( 2 P 1/2, F=3) at 1315.222nm were observed with an intensity of 3x10 -5 cm -1 and 1x10 -5 cm -1 respectively. The small signal gain of I( 2 P 3/2 ,F=4)← I( 2 P 1/2 ,F=3) at different location relative to HN 3 injector along the flow direction also was obtained. The experimental results indicate that the AGIL driven by NF 3 /D 2 /DCl/CF 3 I combustion is feasible.

Singlet oxygen generator is the key of chemical oxygen-iodine laser (COIL) which supplies energy for the system. However, the traditional generators have some drawbacks just as the bigger volume and the lower chemical efficiency. Specific surface area is the important factor restricting the development of singlet oxygen generator. Many researches on increasing specific surface area have been done to improve the performance of singlet oxygen generator. A new type eject singlet oxygen generator was introduced in this paper. Ejector was used in gas-liquid reaction. Liquid ejected through the nozzle with high velocity droved by high pressure, and gas ejected into mixing chamber along the tangent of nozzle. Gas and liquid were broken into many small droplets. Gas and liquid reacted in reaction chamber, then the mixture ejected into separator with very high speed. These droplets can produce mount of gas-liquid interface and increase the chemical efficiency of generator. Many numerical simulations have been done on the new type generator According to the simulations, eject singlet oxygen generator is feasible and has prospect. Therefore ejector may be a better type of singlet oxygen generator.

A novel concept of the chemical production of atomic iodine aimed for application in chemical oxygen-iodine laser was proposed. The method is based on nitrogen trichloride spraying auto-decomposition to generate chlorine atoms which subsequently react with iodine donors. Preliminary experimental and computational studies for the reaction system were explored. The experimental results show efficient generations of excited atomic iodine and computational results reveal that a large degree of atomic iodine can be generated via the reaction system including nitrogen trichloride combustion effluents and iodine donors.

A dedicated CW chemical oxygen iodine mini-laser is constructed and used to probe the two-dimensional (2-D) distribution of small-signal gains in a supersonic CW chemical oxygen iodine laser (CW COIL). The uneven lateral gain distribution may possibly be explained by boundary layer effects.

By means of radio frequency(RF) capacitively coupled discharge, pure CF 3 I and the mixture of CF 3 I and various inert gases were used to produce iodine atom for a chemical oxygen-iodine laser. The dependences of atomic iodine concentration on gas pressure and gas flow rate were studied. In the case of RF frequency of 13.56MHz, output power of 500W, gas pressure of 3.5Torr, pure CF 3 I without any carrier gas ,and CF 3 I flow rate of 1.2SLM, atomic iodine concentration of 4.0™ 10 14 cm -3 was achieved. The concentration of atomic iodine was of the order of 0.4×10cm -3 at p=15Torr in the case of the mixture of CF 3 I and some inert gases, which was lower by one order of magnitude than that of pure CF 3 I. A kinetics modeling was carried out and demonstrated that CF 3 played dominant role in the loss mechanism of atomic iodine. Keywords: iodine atom, RF discharge, dissociate 1. INTRODUCTION In the conventional chemical oxygen-iodine laser (COIL), iodine atom is produced by the following chemical reaction, ( ) 2 ( 3 /

DC discharge characteristics of NF3/He have investigated experimentally at many kinds of experimental conditions, for example, different electrodes material, a few of distance between the two electrodes, flow rates of the gas NF3 or He, a series of series-wound resistances and give the steady and optimum discharge parameters finally. Fluorine atom yield from the DC discharge of NF3/He have studied experimentally and the relationship of fluorine atom yield and the load power is shown for the first time.

A uniform droplet singlet oxygen generator (SOG) has been developed and used to power chemical oxygen-iodine laser (COIL). The uniform droplets images have been caught by a camera. The chlorine utilization, O 2 ( 1 ' ) yield, H 2 O concentration, and laser power have been measured. The maximum power density through the nozzle is 121.3 W/cm 2 . Keywords: Chemical oxygen-iodine laser, singlet oxygen generator, uniform droplet INTRODUCTION Chemical oxygen iodine laser (COIL) is pumped by electronically excited oxygen, O 2 ( 1 ' ). 1 For COIL, singlet oxygen is produced by reacting gaseous chlorine with a basic hydrogen peroxide (BHP) solution according to the know overall stoichiometry Cl 2 + H 2 O 2 + 2KOH zO 2 ( 1 ' ) + 2KCl + 2H 2 O (1) A singlet oxygen generator (SOG) is considered as a “heart” of the COIL since efficiency of the SOG operation and generator output characteristics are crucial in determining the overall efficiency of the lase r system. Several techniques have been used to react chlorine with BHP.

By using emission spectroscopy method and absorption at 1392nm, partial water pressure at the exit of a square pipe-array jet-type singlet oxygen generator (SPJSOG) for chemical oxygen-iodine laser (COIL) was measured. The water vapor fraction was calculated from the partial water pressure in the diagnostic cell when we assumed the water vapor fraction in the diagnostic cell is the same as that in the generator. The results from the two methods showed that the water vapor concentration is less than 0.08 in this SPJSOG during normal operation. The water vapor fraction decreases with the increasing of the pressure in the generator and rises with the increasing of buffer gas flow rate and the basic hydrogen peroxide (BHP) temperature in the case of constant chlorine flow rate. Measurements showed that the change of water vapor fraction due to BHP temperature could be ignored during normal operation. It is indicated that the gas flow velocity is the main reason that affects on the water vapor fraction in COIL. It is proved that the emission spectroscopy method is one of the simple and convenient ways to measure the water vapor concentration in singlet oxygen generator (SOG), especially in real time measurements. But absorption spectroscopy method, as a direct measurement, can give the more factual results of the water concentration.

A Raman scattering system was used to measure the O2 (a1delta) yield end the chlorine utilization in a singlet oxygen generator of chemical oxygen iodine laser with nitrogen diluent. We present the results from the tests that conducted on a 0.1-mol/s jet-type singlet oxygen-iodine generator. On the basis of the current reported uncertainty of the Raman cross section, the error in the yield measurement is calculated to be less than 8%, and the error of the chlorine utilization is 12%.

By means of a microwave generator chlorine diluted by helium was dissociated to chlorine atoms that subsequently reacted with hydrogen azide to produce the excited states of NCl(a 1 Δ). Meanwhile, molecular iodine with carrier gas of helium reacted with atomic chloride to produce atomic iodine which then was pumped to excited state of I( 2 P 1/2 ) by an energy transfer reaction from NCl(a 1 Δ). In this paper, the changes of NCl(a 1 Δ) and NCl(b 1 Σ) emission intensity is presented upon admitting I 2 /He into the stream of Cl/Cl 2 /He/HN 3 /NCl(a 1 Δ)/NCl(b 1 Σ). Moreover, the production of excited state of atomic iodine I( 2 P 1/2 ) dependent on flow rates of gases was also investigated. The optimum parameters for I( 2 P 1/2 ) production are given.

By means of Microwave generator chlorine diluted by helium is dissociated to chlorine atoms that subsequently react with hydrogen azide to produce excited states of NCl(a 1 (Delta) ) and NCl(b 1 (Sigma) ). In this paper, the intensity of NCl(a 1 (Delta) ) and NCl(b 1 (Sigma) ) emission dependent on the flow rates of different gases is studied. Moreover, the production of NCl(a 1 (Delta) ) and NCl(b 1 (Sigma) ) along the reaction tube is also investigated. By using a simple titration method, we obtain the dissociation efficiency of molecular chlorine up to 100 percent at the flow rates of chlorine no more than 1 mmol/s. We also achieve the quenching rate of NCl(a 1 (Delta) ) by Cl 2 is about 4 X 10 -13 cm 3 /sec molec with excess flow rates of chlorine. Finally, the optimum parameters for NCl(a 1 (Delta) ) and NCl(b 1 (Sigma) ) production are summarized.

A multi-kilowatt supersonic chemical oxygen iodine laser (COIL) has been constructed. Two types of jet singlet oxygen generator (SOG) such as tube-array and plate have been tested. An output power of 8.8KW with chemical efficiency of 2 1 .4% was obtained at the chlorine flow rate of 45Ommole/s. The influence of BHP (basic hydrogen peroxide) temperature on the output power of COIL has been studied. And the absolute concentration of O2(1AE) in the jet SOG was measured using the Piston-source method.

A calibrated piston source of light, which simulates a cylindrical-volume source, has bene used to measure the absolute concentration of O 2 (a 1 (Delta) ). It is proved that this Piston Source Method is one of the simplest and most convenient ways to measure the O 2 (a 1 (Delta) ) concentration in a singlet oxygen generator, especially in real time measurements.

The study of singlet oxygen (O-1(2)) emission showed that the O-1(2) could be efficiently produced in the reaction of solid potassium superoxide (KO2) particles with chlorine gas (Cl-2), which only occurred on the surface of solid KO2 particles. The liquid water may accelerate the reaction of Cl-2 with KO2 and make a complete conversion of KO2 to O-1(2). The KO2 had a similar efficiency for O-1(2) production as the alkali metal peroxides (such as Li2O2 and Na2O2) as reacting with Cl-2.

A dedicated continuous wave chemical oxygen iodine mini- laser is constructed and used to probe the 2D distribution of small-signal gains in a supersonic continuous wave chemical oxygen iodine laser. The uneven lateral gain distribution may possibly be explained by boundary layer effects.

The formation of a uniform droplet is the key in a uniform-droplet singlet-oxygen generator (SOG). This paper is mainly on the condition of uniform droplet formation. Factors in uniform-droplet formation, such as basic hydrogen peroxide (BHP) liquid velocity, disturbance frequency, and the pressure distribution in the fluid infusion cavity, were analyzed and optimized in order to improve the performance of the uniform-droplet singlet-oxygen generator. The chlorine utilization, O2(1Δ) yield, H2O concentration, and laser power were measured. The output concentration of O2(1Δ) was as high as 2.94 ×1017/cm3. The maximum power density through the nozzle was 121.3 W/cm2.

This paper examines the action of various metal catalysts on red emitter formation. The chlorine content of chemically generated singlet oxygen was monitored by chemical analysis and chromatography. The presence of chlorine in chemically generated singlet oxygen indicates that chlorine plays some role in red emitter formation. The radiative life of the emitter was calculated from spatial chemiluminescence decay in the chemiluminescence cell. Results showed that red emission is represented by a characteristic spectrum independent of the catalyst used. This observation eliminates the possibility of a metal-containing emitter. A consideration of Cl2, ClO2.O2, Cl2O2, and O4 as possible emitting species is given. Experimental red spectra obtained show a series of fringes which may be caused by quantum interference in a bound-free transition© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.