Showing papers on "Semiconductor optical gain published in 1971"
TL;DR: In this paper, a new technique for measuring the stimulated emission spectrum and optical gain of semiconductor materials was proposed. But it was only applied to CdS crystals at 2°K and showed that net gains as high as 160 cm−1 at λ = 4907 A are possible with ∼ 12MW/cm2 optical pump power density from a nitrogen laser.
Abstract: We report a new technique for measuring the stimulated emission spectrum and optical gain of semiconductor materials. Amplified spontaneous emission is used to determine the gain factor by relating the measured variation in light output to variation in the length of the excitation beam. Results for CdS crystals at 2°K are presented that indicate net gains as high as 160 cm−1 at λ = 4907 A are possible with ∼ 12‐MW/cm2 optical pump power density from a nitrogen laser.
400 citations
01 Apr 1971
TL;DR: In this article, the theory of the molecular hydrogen laser is presented and the operation of the device to generate a fast-rising current pulse which travels down the discharge channel at the velocity of light is described.
Abstract: A unique gas laser system suitable for achieving more than a 100-kW peak power in the vacuum ultraviolet spectral region near 1600 A is described. First, the theory of the molecular hydrogen laser is presented. The novel operation of the device to generate a fast-rising current pulse which travels down the discharge channel at the velocity of light is described. Finally, the experimental verification of lasing and further characteristics of the device are given.
26 citations
TL;DR: In this paper, external spectrally selective elements were introduced into the resonator of an injection semiconductor laser in order to improve the spectral composition of the emitted radiation, and in particular to increase the output power in the single-mode operation.
Abstract: External spectrally selective elements were introduced into the resonator of an injection semiconductor laser in order to improve the spectral composition of the emitted radiation, and, in particular, to increase the output power in the single-mode operation. The following variants were investigated experimentally: a) a composite resonator; b) a resonator with an interference filter; c) two optically coupled Fabry?Perot resonators of different length. An external selective element always affected the emission spectrum of a semiconductor laser. A single longitudinal mode was obtained when the pumping level exceeded the threshold by an amount larger than in ordinary injection lasers. The output power under single-mode conditions ranged up to 0.5?W (in the case of a composite resonator). An investigation was made of the possibility of using an external element for varying the emission wavelength within the gain band of the semiconductor.
19 citations
TL;DR: In this article, it was shown that the tuning rate is a function of the time after the start of the pumping pulse and the pumping current density, and that the behavior of tuning rates is dependent on whether or not lasing action occurs in the crystal under examination.
Abstract: The wavelength at which the stimulated output from a number of electron-beam-pumped semiconductor lasers peaks is a function of the time after the start of the pumping pulse. In general, the output intensity reaches a maximum at short wavelengths considerably before it peaks at the longest. Detailed observations of the wavelength shifts of the peak output as a function of both time and pumping current are reported here for both CdSe and GaAs laser crystals. It is found that the rate of shifting of the wavelength peak (tuning rate) as a function of electron-beam pumping current is very similar in both functional form and magnitude in the two materials. Furthermore, the behavior of the tuning rate is dependent on whether or not lasing action occurs in the crystal under examination. For a crystal in which lasing action is obtained, the tuning rate saturates for pumping current densities above threshold. In contrast, for a nonlasing crystal, the tuning rate is a linearly increasing function of the pumping current density. The implications of these results are discussed with reference to previously reported work concerning shifts with respect to the band edge of the stimulated emission from semiconductor lasers.
13 citations
TL;DR: In this article, a theory of electro-acoustic surface-wave interaction is presented for a layered structure of piezoelectric and semiconductor, where the semiconductor is assumed to be thin compared to both the acoustic wavelength and the Debye length.
Abstract: A theory of electro‐acoustic surface‐wave interaction is presented for a layered structure of piezoelectric and semiconductor. The semiconductor is assumed to be thin compared to both the acoustic wavelength and the Debye length. Diffusion has been taken into account in the analysis. Computed curves of gain are given and the dependence of gain on frequency, carrier concentration, drift velocity, and semiconductor thickness is discussed.
7 citations
TL;DR: In this article, the small signal gain and saturation intensity of a CO 2 -N 2 -He laser were measured as a function of gas flow velocity over the range from 0-10 m/s.
Abstract: Measurements of the small signal gain and saturation intensity of a CO 2 -N 2 -He laser are made as a function of gas flow velocity over the range from \sim 0-10 m/s. The small signal gain increases and the saturation intensity decreases with increased gas velocity. For intermediate flow velocities with a gas transit time in the laser of a second, the gain also depends on the direction of propagation of the amplified beam with respect to the gas flow. The directional dependence is due to an axial gradient in the saturation intensity. The transit time of the gas in the 2.5-m amplifier spans the time required for appreciable generation of CO by dissociation of the CO 2 and the variation of the laser gain with velocity is attributed to the effects of CO on the inversion of the laser medium.
5 citations
TL;DR: In this paper, a technique for stabilizing the resulting frequency separation by locking it to an external frequency source is described, which should be useful in optical heterodyne applications, and the stabilized separation is shown to be useful for optical laser applications.
Abstract: Lasers can be made to oscillate simultaneously at two frequencies by means of anisotropic or nonreciprocal resonator elements. A technique is described for stabilizing the resulting frequency separation by locking it to an external frequency source. The stabilized separation should be useful in optical heterodyne applications.
3 citations
2 citations
TL;DR: In this article, the spectral intensity distribution of the spontaneous omission from semiconductor lasers of n-type GaAs pumped by a 40 kv electron beam is calculated using the theory of recombination statistics.
Abstract: The spectral intensity distribution of the spontaneous omission from semiconductor lasers of n-type GaAs pumped by a 40 kv electron beam is calculated using the theory of recombination statistics. The results obtained are in good agreement with the published data on experiments carried out both at 77°k and 300°K. In particular a hump is obtained in the spectral distribution on the high energy side of the spectrum of the light emitted from n-type GaAs at 77°K when the level of doping is very high. This also is in agreement with the experimental observation reported elsewhere.
1 citations
1 citations
01 Jan 1971
TL;DR: In this article, a time-scanning image converter with a resolution of 5 · 10 − 12 seconds was used to observe the interaction between gallium arsenide injection lasers sharing a common junction.
Abstract: A time-scanning image converter with a resolution of 5 · 10-12 sec was used to observe the interaction between gallium arsenide injection lasers sharing a common junction. A strong optical coupling was maintained through those regions of the junction which were shared by the resonators of different lasers. The absolute value of the absorption coefficient of these regions decreased under the saturating effect of the radiation field of any of the lasers. Finally, this resulted in the switching on or off of one of the lasers by the optical signals of the other lasers. The characteristic times of the transient (switching) processes were of the order of 10-10 sec and the durations of the emitted light pulses were of the same order.
TL;DR: In this article, the threshold characteristics of semiconductor lasers are considered as a function of the doping level and the temperature, and a model of the transitions from a parabolic conduction band to an impurity acceptor band with a Gaussian distribution of the density of states is presented.
Abstract: The threshold characteristics of semiconductor lasers are considered as a function of the doping level and the temperature. Use is made of a model of the transitions from a parabolic conduction band to an impurity acceptor band with a Gaussian distribution of the density of states. The gain and the spontaneous recombination rate are calculated. The dependences of the threshold current, the quasi-Fermi levels, and the laser oscillation frequency on the impurity concentration and the temperature are obtained.