Dual Q-switched laser outputs from a single lasing medium using an intracavity MEMS micromirror array

An intracavity array of individually controlled microelectromechanical system scanning micromirrors was used to actively Q-switch a single side-pumped Nd:YAG gain medium. Two equal power independent laser outputs were simultaneously obtained by separate actuation of two adjacent micromirrors with a combined average output power of 125?mW. Pulse durations of 28?ns FWHM at 8.7?kHz repetition frequency and 34?ns FWHM at 7.9?kHz repetition frequency were observed for the two output beams with beam quality factors M² of 1.2 and 1.1 and peak powers of 253?W and 232?W, respectively.     

The laser pulse from a rf waveguide CO2 laser

The behaviour of a rf-excited waveguide CO₂ laser in the pulse regime is studied experimentally. The specific time sections of the pulse have been defined and described in detail. The output pulse evolution versus input power, pressure of the laser mixture, output coupling, repetition frequency and pulse width has been investigated. The spectral content of the pulse has been analysed. A model explaining the effect of laser tuning during the pulse duration is given. The ultrahigh pulse (UHP), defined as the pulse for which the bulge effect occurs, is predicted. Received: 22 October 2002 / Revised version: 13 January 2003 / Published online: 26 March 2003 RID="*" ID="*"Corresponding author. Fax: +48-71/3203-189, E-mail: eda@zr.ita.pwr.wroc.pl     

Simultaneous emission on 10P and 10R branch lines from a hybrid CO2 laser

The use of cavity length control to obtain multiline emission from a hybrid CO₂ laser has been investigated. We have obtained simultaneous laser oscillation on up to four lines in the P and R branches of the 10 m band by operating the c.w. section above the lasing threshold. For sub-threshold operation of the c.w. section the hybrid laser emission is restricted to the stronger 10P lines.     

TEA CO2激光器序列带的输出特性

 采用双光栅谐振腔和增长放电增益区,进行了TEA CO₂激光器弱线输出特性研究。在CO₂,N₂,He气体体积比为0.16∶0.21∶0.63,总压强为57.3 kPa情况下,获得6条11 μm波长附近弱线(序列带和热带)激光输出,谱线脉宽为400 ns左右。研究了011-030带的P19线的输出波形和能量,结果表明：谱线输出能量随光栅中心的位移变化而变化,当光栅中心在放电区中心轴线上时输出最强,最大输出能量达几百mJ。     

TEA CO2激光器序列带的输出特性

采用双光栅谐振腔和增长放电增益区,进行了TEA CO2激光器弱线输出特性研究。在CO2,N2,He气体体积比为0.16∶0.21∶0.63,总压强为57.3 kPa情况下,获得6条11 μm波长附近弱线(序列带和热带)激光输出,谱线脉宽为400 ns左右。研究了011-030带的P19线的输出波形和能量,结果表明：谱线输出能量随光栅中心的位移变化而变化,当光栅中心在放电区中心轴线上时输出最强,最大输出能量达几百mJ。     

Effect of detuning on the lasing dynamics of a CO2 laser with a saturable absorber in the resonator

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 3, pp. 457–461, September, 1991.     

cw far-infrared lasing in15NH3, stark resonantly pumped by a CO2 or N2O laser

CF₂ClCF₂Cl and ethyl acetate have absorption bands of similar width centered at the same frequency. Kinetics of the decompositions of these compounds by a cw CO₂ laser have been studied over a range of laser frequencies extending to 25 cm^?1 below band center. At constant translational temperature and pressure, the CF₂ClCF₂Cl rate constant changes by more than 200 with frequency, while the corresponding change for ethyl acetate is at most 3. The effect of laser frequency increases with increasing CF₂ClCF₂Cl pressure, while the reverse is true in ethyl acetate. Arrhenius plots show activation energies independent of both frequency and pressure.     

Dual excimer and CO2 laser etching studies of polyethylene terephthalate

Polyethylene terephthalate (PET) films preheated with a pulsed CO₂ laser have been ablatively etched with an XeCl laser. The observed reduction in ablation threshold, from 170 to 140 mJ cm^–2, is consistent with a thermal mechanism for XeCl laser ablation of PET. Transient changes in the UV absorption coefficient of PET caused by heating with pulsed CO₂ laser radiation have also been studied and a significant increase in absorption observed at 308 nm. Permanent changes in the ultraviolet absorption of PET following exposure to low fluence XeCl laser radiation are also reported.     

Four-branch oscillation from a dual-polarization cavity CO2 laser

We report here for the first time multiline oscillation of a cw-CO₂ laser on all the four branches 10P, 10R, 9P, and 9R where all laser wavelengths share a common gain medium. The 9R, 9P and 10R branch lines lased at the expense of the high-gain 10P branch lines for which the cavity offered very high transmission losses. The 10P(20) line was made to lase by constructing another cavity with orthogonal polarization, thereby easing the strong competition between this line and the relatively low-gain 9R, 9P and 10R branch lines within the gain medium which is common to both cavities.     

优化封离型CO2激光工作气体的动力学机理研究

详细讨论了封离型CO2激光器中CO2,N2和He三混合气体含量被优化组合后的激光动力学机理.气体优化可以提高激光输出功率的主要机理是通过适当增加N2含量,使N2激发态与CO2激光上能级的碰撞频率增加,提高了激光能级粒子数密度和相对布居数.同时,适当减少CO2含量,使总的电子动量输运碰撞频率减小、放电电流增大,导致增加激光上转动能级的弛豫速率和减小能级寿命,从而提高了谐振腔内的激光饱和光强.     

Stark spectroscopy with the CO laser: The ν3 fundamental band of H2CO

The ν₃ fundamental band of H₂CO (CH₂ scissoring motion) has been studied by means of CO laser Stark spectroscopy and conventional infrared absorption spectroscopy. The primary aim of the work was to determine the dipole moment of H₂CO in the v₃ = 1 state, and the value determined was 2.3250 ± 0.0025 D. The spectrum was analyzed with the inclusion of the Coriolis interactions among ν₃, ν₄, and ν₆ so that “true” rotational constants were determined for ν₃; “effective” constants obtained by ignoring these interactions were also determined. The ν₃ band origin was determined to be 1500.174 ± 0.002 cm^?1. The H₂CO spectrum was also used as a means of determining the frequencies of some ¹³C¹⁶O and ¹²C¹⁸O laser lines in the 1500 cm^?1 region relative to ¹²C¹⁶O lines.     

Diode laser spectra of the ν2 band of H212CO and H213CO

The Q-branches of the ν₂ (CO stretch) band of H₂¹²CO and H₂¹³CO have been studied in high resolution using an infrared diode laser. Accurate upper state constants, including A, B, C, Δ_J, Δ_JK, Δ_K, and H_K, were determined from an analysis of the data for 97 lines of H₂¹²CO and 79 lines and H₂¹³CO and compared with previous reported values. Band centers were also determined and reported as 1746.009 ± 0.002 cm^?1 for H₂¹²CO and 1707.981 ± 0.002 cm^?1 for H₂¹³CO.     

Unidirectional high intensity narrow-linewidth lasing from a planar random microcavity laser

Lasing was achieved in a new type of random laser: the planar random microcavity laser. The laser consists of a planar microcavity with a random gain layer. Optical confinement by the two-dimensional random cavity and the one-dimensional planar microcavity drastically reduces the number of resonant modes. As a result, the laser output is highly directional (the divergence angle is 1.68 degrees) with an extremely narrow-linewidth and ultralow threshold. All these phenomena are explained in terms of the coupling of random cavity modes and planar microcavity modes. The results demonstrate an important step towards applications of random lasers.     

Intense directional lasing from a deformed square-shaped organic-inorganic hybrid glass microring cavity

Intense directional light emission from a deformed square-shaped organic light-emitting microring cavity was observed. The ring cavity was a dye-doped organic-inorganic hybrid glass film coated upon a square-shaped fiber. From the near-field and far-field emission patterns and their emission spectra we found, for the first time to our knowledge, the simultaneous existence of chaotic whispering-gallery modes and four-bounce reflection modes. The two types of mode have different emission directions, different lasing thresholds, and different spectral linewidths. High-contrast angle-modulated light emission was also observed. We could control modulation and angular spread of emission by controlling the deformation of the cavity.     

Spatiotemporal instabilities from a transversely excited atmospheric CO2 laser

Local spatiotemporal instabilities in a TEA CO₂ laser have been studied. Their evolution was studied from the beginning of the gain switch peak to the quasistationary state in the collisional transfer tail of the pulse.The dynamics varies when the diameter of an intracavity aperture is changed. In the TEM₀₀ mode an ordered axial mode beating is observed. In transverse multimode regime irregular fluctuations are observed. In this case signals from two different points taken in the near field show a low cross-correlation. The application of the Grassberger-Procaccia algorithm to the irregular signals shows a good slope convergence towards a value of 2.5, pointing to a chaotic deterministic behaviour.     

Independently controllable multiline emission from a TEA CO2 laser

Spatial separation of wavelengths in a CO₂-laser resonator helps to avoid competitions. We have achieved this by means of a nearly concentric resonator with a grating or prism in its center. Thus, we demonstrated independent multiline emission with a variety of output spectra. The temporal sequence of the lines was conveniently controlled by varying their losses.     

Dual wavelength operation in diode-end-pumped hybrid vanadate laser

Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd³⁺-doped birefringent YVO₄ and GdVO₄ crystals is demonstrated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition rate is obtained with 32 ns FWHM pulse duration corresponding to 25 kW of the peak power. The intensity and the polarization of the individual spectral components can be easily controlled by changing the relative gain and the relative orientation of the two crystals. The resulting pulsed dual-wavelength laser has the potential to be used as a source for generating terahertz radiation.