Increase In Light Output Research Articles

The control of polarization of laser diodes

The mode-competition phenomena are studied through three experiments. At first, in double-heterostructure laser diodes with thick active layers, TE and TM modes tend to coexist and the mode competition between these two modes is observed from the correlation of the light outputs of these two modes where the increase of light output of one mode tends to decrease the light output of other mode. In a laser diode operating with an external reflector, the increase of light output for the TE mode leads to the decrease of light output for the TM mode. In case the external reflector is set to deviate from the parallel plane to the cleaved surface of the laser diode, the TM-mode component tends to its magnitude, even if the inherent mode of this diode is TE. In the experiment of external light-beam irradiation onto a laser diode, the light intensity of one mode is decreased by an incidence of light beam having another mode from the other laser diode. In this experiment, the significance of a gap distance between the two laser diodes is confirmed clearly, where the two laser diodes interact with each other through the light beam.

Properties of high pressure nitrogen-argon and nitrogen-xenon gas scintillators

Investigations of scintillation light output and energy resolution have been made at pressures up to 90 atm in gaseous mixtures of nitrogen with both argon and xenon by stopping of 210Po-alpha particles. In the absence of a wavelength shifter, the N 2Ar mixtures gave a maximum pulse height at a ratio of nitrogen to argon partial pressures r N 2 Ar ≊ 0.2 . However, when using the wavelength shifter diphenyl stilbene (DPS), the measured light output was much larger to lower values of r N 2 Ar , whereas for r N 2 Ar > 0.2 pulse height and energy resolution of the studied N 2Ar mixtures were roughly identical with and without DPS. The N 2Xe gas mixtures exhibited a similar dependence of pulse height and energy resolution to that of the N 2Ar mixtures employing DPS, but the pulse heightwas larger by a factor of about 7. A 40 atm 50% N 2−50% Xe gas scintillator showed an energy resolution ΔE E = 0.25 , while an 80 atm 75% N 2−25% Xe scintillator gave ΔE E = 0.6 . The pulse height from the 80 atm N 2Xe scintillator was smaller by a factor of about 240 than the pulse height from a 20 atm pure Xe gas scintillator, but larger by a factor of about 20 than the pulse height from a 75 atm pure N 2 gas scintillator. The N 2Xe mixtures showed a remarkable increase of light output as the temperature of the gas was decreased.

Single-mode operation of diode lasers coupled to hemispherical resonators

Uncoated GaAs diode laser of different structures are coupled to external spherical mirrors. The emission characteristics of these systems are investigated. Mode selection effects are observed and single-mode operation may be achieved in the hemispherical resonator case if the length of the external cavity resonator is close to the optical diode length. Low coupling losses between the diode and the resonator are characteristic in this case and result in an increase of light output at coupling.

Analysis of Characteristics of Xenon Flashtubes by means of Experimental Equations.

Experimental equations of the tube voltage, the cureent and the flux of xenonflashtubes are established. Electrical and optical characteristics are calculated by these three equations and are discussed for different applied voltages and tube lengths.The following results are obtained:1. The maximum current density, the maximum luminous flux and light output increase with an increasing applied voltage and a shorter distance between electrodes.2. Duration of more than half flux of its maximum being maintained decreases with an increasing applied voltage and a decreasing the tube length.3. The efficiency increases with an increasing applied voltage and a decreasing tube length. The rate of its increase becomes smaller as the tube length decreases below 5cm.

Enhanced Afterglow in Neon by Removal of Electrical Excitation

An unusual increase in light output results when a neon strobe tube is suddenly short-circuited during the transient. Experimental measurements have been made of the emitted light from the discharge when the capacitor is short-circuited at different times after the initiation of the discharge.

Enhanced Afterglow in Neon by Removal of Electrical Excitation

An unusual increase in light output results when a neon strobe tube is suddenly short-circuited during the transient. Experimental measurements have been made of the emitted light from the discharge when the capacitor is short-circuited at different times after the initiation of the discharge.

How much do wave length shifters used for Čerenkov counters scintillate?

The increase in light output of liquid Cerenkov counters obtained by addition of wave length shifting substances (as suggested by many authors) has been studied. It is shown that most of the observed increase is due to scintillation and not to actual wave length shifting. Crystalline sodium salycilate coating of the counter walls has also been used for the same purpose. Its average quantum efficiency is found to be relatively high but its practical use is limited by the fact that its reflectivity in the visible is lower than that of MgO.