共查询到20条相似文献,搜索用时 15 毫秒
1.
The change of operating parameters above threshold of (Ga, Al)As injection lasers with aging time was calculated assuming a uniform mode of degradation mechanism with temperature-dependent degradation rates. In the calculation, the degradation rate for the threshold current was assumed to be temperature dependent, but not explicitly dependent on aging time and pumping current. Optical output power was kept constant during aging. The calculated time variation of laser parameters predicts a runaway after an initial slow rise. The mathematical model thus provides the means to correlate time-to-failure data with initial degradation rates and permits the evaluation of the influence of various laser parameters on lifetime. A selected group of laser diodes were aged at 80 °C under the conditions specified by the model. Degradation rates for the threshold current varied between4 times 10^{-5} and5 times 10^{-4} h-1. These would extrapolate to lifetimes in excess of 10 000 h at the elevated temperature for half of the diodes in reasonable agreement with experimental values obtained by others. 相似文献
2.
Small-signal gain and saturation parameter of a transverse-flow CW oxygen-iodine laser 总被引:1,自引:0,他引:1
Watanabe K. Kashiwabara S. Sawai K. Toshima S. Fujimoto R. 《Quantum Electronics, IEEE Journal of》1983,19(11):1699-1703
The small-signal gain and saturation parameter of a transverse-flow CW oxygen-iodine laser have been experimentally obtained for the first time from output power measurements made as a function of the cavity losses without using a CW probe laser. These measurements typically yieldalpha_{0} simeq 0.045 m-1andI_{s} simeq 0.44 kW/cm2for a Cl2 flow rate of1.4 times 10^{-3} mol/s with an I2 flow rate of4 times 10^{-6} mol/s. The dependences of the small-signal gain and saturation parameter have been also found on the Cl2 flow rate. These behaviors are qualitatively explained by a simple two-level model. 相似文献
3.
Four new laser lines, two in atomic Zn at 481.1 and 472.2 nm and two in atomic Cd at 508.6 and 480.0 nm, are reported. The analog laser lines in Hg at 546.1 and 435.8 nm are studied further. These lines correspond to the transitionsn^{3}S_{1} rightarrow (n-1)^{3}P_{2} andn^{3}S_{1} rightarrow (n-1)^{3}P_{1} of the triplet system of the metals. The medium in the three cases is MI2 (M = Zn, Cd, or Hg) vapor at about 1 mbar and the pump is a KrF laser at 248 nm. The blue-green superfluorescent pulse power is in the kilowatt range, with a pulse duration of about 1 ns. The pumping process must involve more than one photon. A sequential three-photon pumping process is proposed for the three cases. 相似文献
4.
Tunable alexandrite lasers 总被引:6,自引:0,他引:6
Walling J. Peterson O. Jenssen H. Morris R. O'Dell E. 《Quantum Electronics, IEEE Journal of》1980,16(12):1302-1315
Wavelength tunable laser operation has been obtained from the solid-state crystal alexandrite (BeAl2 O4 :Cr3+) over the continuous range from 701 to 818 nm. The tunable emission was observed at room temperature and above in a homogeneously broadened, vibronic, four-level mode of laser action. In this mode the laser gain cross section increases from7 times 10^{-21} cm2at 300K to2 times 10^{-20} cm2at 475K, which results in improved laser performance at elevated temperatures. Efficient 2.5 percent, low-threshold (10 J) operation has been obtained with xenon-flashlamp excitation of the 6 mm diameter × 76 mm length laser rods. Output pulses of greater than 5 J and average power outputs of 35 W have been demonstrated, limited by the available power supply. The emission is strongly polarizedEparallelb , with a gain that is 10 times that in the alternate polarization. The 262 μs, room-temperature fluorescence lifetime permits effective energy storage andQ -switched operation. TunableQ -switched pulses as large as 500 mJ have been obtained with pulsewidths ranging between 33 and 200 ns depending on the laser gain. Laser action has also been demonstrated on the high-gain (3 times 10^{-19} cm2emission cross section)R line at 680.4 nm and is also polarizedEparallelb . This three-level mode is analogous to the lasing in ruby except that the stimulated emission cross section in alexandrite is ten times larger than for ruby. 相似文献
5.
Hori H. Kitayama Y. Kitano M. Yabuzaki T. Ogawa T. 《Quantum Electronics, IEEE Journal of》1983,19(2):169-175
Experimental results are shown on the frequency stabilization of a GaAlAs laser using a Doppler-free spectrum in the saturated absorption of the Cs-D2 line at 852.1 nm. The frequency stability (Allan variance) between3.0 times 10^{-12} and1.0 times 10^{11} was obtained at the averaging time between 0.1 and 1000 s. 相似文献
6.
The population densities of the He(I)2^{3}S and2^{3}P levels and the Cd(II) ground level were experimentally determined with the modified absorption method in a positive column He-Cd laser discharge with little iodine. The population densities of the upper and lower laser levels of the Cd(II) 441.6 nm line were also obtained with the modified absorption method and the gain measurement. From these results, the mechanism of the increase in the Cd(II) 441.6 nm laser power with the addition of iodine was made clear. 相似文献
7.
Savitski V. G. Schlosser P. J. Hastie J. E. Krysa A. B. Roberts J. S. Dawson M. D. Burns D. Calvez S. 《Photonics Technology Letters, IEEE》2010,22(4):209-211
8.
Basov N. Baranov V. Chugunov A. Danilychev V. Dudin A. Kholin I. Ustinovskii N. Zayarnyi D. 《Quantum Electronics, IEEE Journal of》1985,21(11):1756-1760
A high-pressure (p = 3.5 atm) electroionization laser operating on the5d-6p xenon atomic transitions is investigated for a pumping pulse duration range up to 30 μs. An output energy of more than 60 J has been achieved with an Ar-Xe mixture and an active volume of 10 1. The angular divergence of the radiation was about5 times 10^{-5} rad. The advantages of such laser systems for industrial use is discussed. 相似文献
9.
The photoionization cross section of excited atomic selenium, Se(1S0 ), obtained by photodissociation of OCSe, has been measured in the wavelength region of 170-175 nm using a tunable xenon laser. A minimum value, at 172 nm, was found to be1.2 times 10^{-20} cm2, approximately ten times less than a recently calculated value. The photodissociation cross section for OCSe, at the same wavelength, was found to be0.8 times 10^{-16} cm2, in good agreement with published work. The effect of an election cooling buffer gas upon the electron production from excited selenium was also investigated. 相似文献
10.
Murakami T. Ohtaki K. Matsubara H. Yamawaki T. Saito H. Isshiki K. Kokubo Y. Shima A. Kumabe H. Susaki W. 《Quantum Electronics, IEEE Journal of》1987,23(6):712-719
A very narrow-beam and high-power laser which has a thin tapered-thickness active layer is developed. The property of LPE on a ridged substrate is utilized to obtain the thin tapered-thickness active layer. In the T3laser, the active layer is thinner near the mirror than in the inner region. The main feature of the T3laser is the independent control of the beam divergence perpendicular to the junction (theta_{perp} ) and the threshold current (Ith ). That is, the narrow beam is obtained with little increase ofIth . Thustheta_{perp} as narrow as 10° has been obtained withIth about 60 mA. The large near-field spot size of the laser is also suitable for high-power operation. The maximum output power of 120 mW in the fundamental transverse mode has been realized for a laser emitting at 780 nm. Stable 30 mW operation at 50°C has been confirmed over 7000 h. 相似文献
11.
Second-harmonic generation (SHG) has been observed in KB5 O8 ċ 4H2 O (KB5) between 217.1 and 315.0 nm by angle tuning in a single crystal using a single cut. A conversion efficiency of 9.2 percent was observed for type I noncritical phase matching at 217.1 nm for a peak power of 15 kW at 434.2 nm. The nonlinear coefficients d31 and d32 are estimated to be approximately1.1 times 10^{-10} ESU (4.0 times 10^{-25} m/V) and0.08 times 10^{-10} ESU (0.29 times 10^{-25} m/V), respectively. 相似文献
12.
A long-pulse Cr:Nd:GSGG laser was operated at almost 2 J output energy and almost 5 percent efficiency, using an uncooled pump cavity. An Nd:YAG rod in the same pump cavity produced 3.75 percent efficiency. Using a water-cooled pump cavity of standard design, the thermal focusing of Cr:Nd:GSGG was found to be almost six times that of Nd:YAG for the same flashlamp input energy. The thermal birefringence of the GSGG was also observed to be significantly higher than that of YAG. The performance of aQ -switched Cr:Nd:GSGG laser was characterized and compared to the predictions of a mathematical model for the laser. This yielded an estimate of4.2 times 10^{-19} cm2for the peak stimulated emission cross section of Nd3+in GSGG. Using the same technique for Nd:YAG yielded a value of9 times 10^{-19} cm2. 相似文献
13.
A new laser oscillation has been observed in a pulsed discharge of He and SnCl4 . This oscillation at 1.061 μm corresponds to the5sSp^{3} ^{3}Dmin{1}max{o} rightarrow 5s^{2}5p6p ^{3}P_{2} transition in Sn(I). 相似文献
14.
Ellipse rotation studies in laser host materials 总被引:3,自引:0,他引:3
Using a TEM00q near Gaussian mode ruby laser system we report the first experimental measurements of intensity induced changes of optical polarization (ellipse rotation) in a cubic crystalline medium, YAG, for which we obtain the nonlinear susceptibilitieschi_{3}^{1221} (- omega, omega, omega, -omega) = 6.34 times 10^{-15} ESU andfrac{1}{2} (chi_{3}^{1111} + chi_{3}^{1221} - 2chi_{3}^{1212}) = 7.18 times 10^{-15} ESU, accurate to better than ±7 percent relative tochi_{3}^{1221} (- omega,omega,omega, -omega) for liquid CS2 . These values are compared with further results obtained for fused quartz and two laser glasses. Moreover, by time resolving the ellipse rotation data we demonstrate the capability to plot ellipse rotation versus input power on a single laser shot, thus increasing the practical feasibility of the technique and introducing the possibility of resolving transient contributions to the measurement. 相似文献
15.
In order to improve the performance of the \(\hbox {Pr}^{3+}\)-doped fiber laser, the optimum fiber length and reflectivity of mirrors, the maximum output power, the lasing threshold, and the slope efficiency are needed to be estimated. In this work, a \(\hbox {Pr}^{3+}\)-doped fiber laser is considered with fiber Bragg gratings (FBG) as reflectors and an injected pump power in one side. To do so, the rate and power propagation equations of the \(\hbox {Pr}^{3+}\)-doped fiber laser are solved numerically by finite difference method and the boundary conditions are obtained by shooting method in an iterative process. The effect of some structural parameters such as the laser background loss, the pump power, the \(\hbox {Pr}^{3+}\) dopant concentration, and the reflectivity coefficient of FBG2 on the performance of laser is studied, and the optimum values for fiber length and reflectivity of FBG2 are obtained. 相似文献
16.
Shao-Chung Hsu Hoi-Sing Kwok 《Quantum Electronics, IEEE Journal of》1987,23(11):2015-2019
The output of a picosecond cascade-pumped controlled transient oscillation (CTO) dye laser has been amplified to the millijoule level. Single-mode operation and frequency selection with a spectral width of 0.2 nm were achieved by using an angle-tuned narrow-band interference filter. A plasma shutter was employed as a pulse clean-up device for these high-power laser pulses. This device had a transmission of 86 percent and provided background-free operation for the laser system. Sychronizable output pulses with an energy of 2 mJ and a duration of 20 ps at 10 pps were routinely produced. The gain of the amplifier chain was about7.5 times 10^{4} . 相似文献
17.
《Electron Device Letters, IEEE》2009,30(3):272-274
18.
Pulsed argon-ion lasers show several interesting properties at high currents. To understand the inversion mechanism, the plasma parameters, electrical conductivity, electron temperature, and electron density were measured with the double-probe method for the pressure range from 15 to 50 mtorr in a 6-mm-bore tube. When the discharge current increases from 100 to 700 amperes at the optimum pressure for laser oscillation, these parameters increase from 250 to450Omega^{-1}cdot cm-1, from8 times 10^{4} to10^{5}deg K, and2 times 10^{14} to 1015cm-3, respectively. At the maximum electron density, the percent of ionization appears to be in excess of 100 percent, as a result of the pinch effect and double ionization. It is certain that this ring discharge is at least ionized very strongly. In a 10-mm-bore tube, only the electron temperature and density were measured. The current dependence of the laser output power at high currents is interpreted with those results. Excitation mechanisms of high-current argon-ion lasers are discussed with experiments and theories for strongly ionized plasmas. 相似文献
19.
An intracavity laser technique has been used to study the absorption of electron-beam pumped Ne/Kr/F2 gas mixtures (196 and 300 K) in the "blue wing" of the Kr2 F emission continuum. The experiments were conducted at 358 nm using theupsilon' = 0 rightarrow upsilon" = 1 transition of the N2 (C rightarrow B ) laser. Comparing the results with the predictions of a computer model, the species primarily responsible for absorption have been identified as Ne+2 , Kr+2 , and Kr2 F*. The photoabsorption cross sections for Ne+2 and Kr2 F (Kr+2 F-) at 358 nm have been estimated to be8.1 cdot 10^{-19} and5.4 cdot 10^{-18} cm2, respectively. The Kr2 F* absorption cross section is roughly 20 percent of that reported for Kr+2 at the same wavelength. The fluorescence efficiency of Kr2 F* ine -beam excited 94.93 percent Ne/5 percent Kr/0.07 percent F2 (P_{total} = 4000 torr) gas mixtures has been found to be a factor of 2.8 higher than that of the N2 (C rightarrow B ) band in Ar/5 percent N2 mixtures. Also, the rate constant for quenching of Kr2 F* by F2 was measured to be(4.1 pm 0.5) cdot 10^{-10} cm3. s-1at 300 K and(3.0 pm 0.5) cdot 10^{-10} cm2. s-1at 196 K. 相似文献
20.
Chicklis E. Naiman C. Esterowitz L. Allen R. 《Quantum Electronics, IEEE Journal of》1977,13(11):893-895
Laser operation of the5S2 →5I7 transition in 2 percent Ho:YLF at room temperature is reported. Oscillations atlambda = 750 nm were obtained in flashlamp and dye laser pumped experiments. Thresholds of 4 J/cm and3 times 10^{-4} J/cm were observed in flashlamp and laser pumped operation, respectively. The 750-nm transition in the Ho:YLF is a four-level laser with a stimulated emission cross section ofsigma = 9.7 times 10^{-19} cm2. 相似文献