A metastable argon laser operating at 912 nm has been demonstrated by optically pumping with a pulsed titanium sapphire laser to investigate the temporal dynamics of an Advanced Noble Gas Laser (ANGL). Metastable argon concentrations on the order of 10<sup>11</sup> cm<sup>-3</sup> were maintained with the use of a radio frequency (RF) capacitively coupled discharge. The end-pumped laser produced output powers under 2 mW of average power with pulse lengths on the order of 100 ns. A comparison between empirical results and a four level laser model using longitudinally average pump and inter-cavity intensities is made. An alternative, highly-efficient method of argon metastable production for ANGL was explored using carbon nanotube (CNT) fibers.
A critical parameter for understanding the performance of Chemical Oxygen Iodine Lasers is the yield of singlet oxygen produced by the generator. Off-Axis Integrated Cavity Output Spectroscopy (Off-Axis ICOS) has been utilized to measure the absolute density of both ground-state and singlet oxygen in the cavity of a COIL laser.
Radio frequency discharge CO overtone lasing with output power of 50 W was demonstrated with supersonic cooling system. The lasing was observed on 9→7, 10→4 and 11→9 vibrational transitions at around 2.7 μm wavelength. Fundamental band lasing was observed within 4.9 - 5.7 μm spectral range. Output power of 2.1 kW with efficiency of 21% was obtained in fundamental band. Modeling experiments on electron-beam sustained discharge overtone CO laser demonstrated that the time interval needed to populate high vibrational levels by W pumping is considerably more than transit time from the supersonic nozzle to laser resonator axis in the RF facility. Possibilities of supersonic overtone CO laser design improvement, for instance, gas pre-cooling and excitation in supersonic cavity were discussed.
Characteristics of CW CO laser with supersonic gas flow are discussed. Radio frequency discharge CO overtone (V+2→V) lasing with output power 50 W was demonstrated with gas cooling due to supersonic expansion. The overtone lasing was observed on 9→7, 10→8 and 11→9 vibrational transitions within spectral range 2.6-2.7 μm. The laser active medium length was 10 cm. The small signal gain on the overtone transitions was estimated to be 0.1 m<sup>-1</sup>. Fundamental band (V+1→V) lasing was observed within 4.9 - 5.7 μm spectral range. In fundamental band output power 2.1 kW with efficiency 21% was obtained, with typical small signal gain being about 1 m<sup>-1</sup>. Modeling experiments on electron-beam sustained discharge facility were carried out at experimental conditions (gas pressure, temperature) corresponding to those of supersonic gas flow. Possibilities of supersonic overtone CO laser design improvement to obtain overtone lasing on highly excited vibrational transitions of CO molecule corresponding to the spectral range ~3-4 micron are discussed.
Radio frequency (RF)-excitation of carbon monoxide (CO) in a supersonic cavity with only a 10 cm gain length has yielded an observed fundamental band (Δv=1) multi-line lasing output power of 2.1 kW utilizing a one-pass resonator, with an electrical efficiency of 21%. More importantly, this work generated 50 W of overtone multi-line lasing around 2.7 micron. This was the first time lasing on CO overtone bands (Δv=2) had been demonstrated with a RF-pumped supersonic system.
A review of recent advances in chemical laser technology is presented. New technology and concepts related to the Chemical Oxygen Iodine Laser (COIL), All Gas-phase Iodine Laser (AGIL), and HF Overtone Laser are discussed.
Temporal behavior of small signal gain (SSG) for a frequency tunable first-overtone CO laser has been studied both experimentally and theoretically. The laser operates on highly excited vibrational transitions from 20→18 up to 38→36 that correspond to laser wavelength range between ~3 and 4 microns coinciding to atmospheric 'transparency window'. Maximum SSG comes up to 0.4 m<SUP>-1</SUP>. It is shown that multiquamtum and asymmetric VV exchange has to be taken into account when analyzing processes of population formation on high vibrational transition.
Output characteristics of a pulsed e-beam controlled discharge laser operating at the first-overtone (FO) transitions ((Delta) V equals 2) of CO molecule have been studied both experimentally and theoretically. Various sets of dielectric mirrors with high reflectivity in the range of the overtone spectrum have been used for the laser resonator. Multiwavelength lasing has been obtained in the wide spectral range of 2.5 - 4.1 micrometers on vibrational transitions from 6 yields 4 up to 37 yields 35. Maximum output efficiency 11%, the highest of eve laser, has been experimentally obtained for the broad band multiline FO CO laser. Maximum specific output energy (SOE) is 50 J/I Amagat. FO CO lasing was observed within an initial gas temperature interval of 100 - 220 K. Spectral characteristics of the overtone laser operating on a selected set of vibrational bands have been analyzed theoretically. Theoretical calculations based on the experimental data predict that multiline FO CO laser efficiency can be increased up to 20%. The experiments with pulsed FO CO laser using diffraction grating as a frequency selective element demonstrated a feasibility of a development of frequency tunable single line pulsed FO CO laser. Tunable FO CO lasing on wavelengths from 2.7 up to 4.2 micrometers corresponding to vibrational transitions from 13 yields 11 up to 38 yields 36 was obtained. The maximum SOE came up to 2.8 J/I Amagat, single line output efficiency being up to 0.6%.
Single line, frequency tunable lasing was observed in an optically pumped, repetitively pulsed, room temperature CO laser for the first time. The R(0) and R(7) ro-vibrational transitions in the (2,0) overtone of CO at 2.3 micrometer were optically pumped with a high-energy optical parametric oscillator (OPO). Single line lasing was observed on (2,1) P(2)-P(17) transitions and R(0)-R(11) transitions (covering wavelengths within the range 4.6 - 4.9 micrometer) when using a diffraction grating as the spectrally selective reflector of the laser resonator. The observed CO laser pulse lengths were approximately 10<SUP>-7</SUP> seconds with peak power being up to 10<SUP>4</SUP> W. The influence of CO pressure, addition of buffer gas (He, Ar), Q-factor of the laser resonator, and pump pulse energy on CO laser pulse temporal characteristics and output energy spectral distribution was studied experimentally.
Tunable single-line first-overtone (FO) CO lasing on wavelengths from 2.7 up to 4.2 micrometer corresponding to overtone vibrational transitions from 13 yields 11 up to 38 yields 36 on 413 ro-vibrational lines was experimentally obtained. A parametric study of energetic and spectral characteristics of the single-line FO CO laser was carried out. Energy distribution over ro-vibrational lines was measured. The maximum specific output energy (SOE) came up to approximately 3 J/l Amagat, with single-line output efficiency being up to 0.6%. For the first time, a multi-quantum theoretical model was used to describe the tunable single-line FO CO laser. This multi-quantum approach demonstrated better agreement between theoretical calculations and observed experimental data for laser output as a function of vibrational quantum numbers.
Output characteristics of a pulsed e-beam controlled discharge laser operating on the first-overtone (FO) transitions (?V=2) of CO molecule have been studied both experimentally and theoretically. Various sets of dielectric mirrors with high reflectivity in the range of the overtone spectrum have been used for the laser resonator. Multiwavelength lasing has been obtained in the wide spectral range of 2.5 - 4.1 µm on vibrational transitions from 6?4 up to 37?35. Maximum output efficiency as high as 11% has been experimentally obtained for the broad band FO CO laser. Output efficiency of the laser operating on a few vibrational bands within the relatively narrow spectral range 2.5-2.7 µm comes up to 5% at entirely suppressed fundamental band (?V=1) lasing. FO CO lasing was observed within an initial gas temperature interval of 100-220 K. Spectral characteristics of the overtone laser operating on a selected set of vibrational bands have been analyzed theoretically. Theoretical calculations based on the experimental data predict that multiline FO CO laser efficiency can be increased up to 20%.