Showing papers on "Quantum dot laser published in 1973"
TL;DR: Saturation of spontaneous emission intensity from stripe-geometry double-heterostructure junction lasers has been observed for currents from threshold up to three times threshold as discussed by the authors, and the observed saturation depends upon the spatial uniformity of the saturated gain obtained in a laser with a thin active region (sim 0.2-0.3 µm) and weak optical confinement.
Abstract: Saturation of the spontaneous emission intensity from stripe-geometry double-heterostructure junction lasers has been observed for currents from threshold up to three times threshold. The present observation of saturated luminescence depends upon the spatial uniformity of the saturated gain obtained in a laser with a thin active region ( \sim0.2-0.3 \mu m) and weak optical confinement. In lasers with thicker active regions ( \sim1 \mu m) and stronger optical confinement, the spontaneous emission does not saturate at threshold but continues to increase with current at a reduced rate. The increasing emission is shown to originate in spatial regions where the field intensity is low and consequently the gain is not saturated. At pumping levels high above threshold, the nonuniform saturation of the gain (transverse spatial hole burning) leads to increased gain and finally oscillation for other transverse modes.
43 citations
TL;DR: In this article, the spontaneous carrier life time of DH-(GaAl)As was measured as 2-5 ns, and the bit rate of 200 Mbits/s was examined.
Abstract: The pulse modulation of DH-(GaAl)As lasers at a bit rate of 200 Mbits/s was examined. To reduce the variation of the lasing pulse peak and lasing delay time due to combinations of "1" and "0" bits, prepumping condition and the damped oscillation parameters are important. The spontaneous carrier life time of DH-(GaAl)As lasers was measured as 2-5 ns.
24 citations
Patent•
IBM1
TL;DR: In this article, a semiconductor laser device having an enclosed laser cavity is disclosed, which is accomplished, in one instance, by surrounding the laser active region on all side surfaces with a higher band gap material which also has a lower index of refraction.
Abstract: A semiconductor laser device having an enclosed laser cavity is disclosed. The semiconductor laser is of the heterostructure type and embodiments of single and double heterostructures are disclosed. In both of the heterostructure devices disclosed, the side surfaces of the active region are well defined. This is accomplished, in one instance, by surrounding the laser active region on all side surfaces with a higher band gap material which also has a lower index of refraction. Thus, the laser cavity is partially enclosed by a semiconductor material on one conductivity type of a band gap higher than the band gap of the material of the laser cavity. The remaining portion is enclosed by a band gap material higher than the material of the laser cavity but is of opposite conductivity type to the first mentioned higher band gap material. In another instance the side surfaces of the laser active region are partially surrounded by a high band gap material and partially by a region of opposite conductivity type to the active region; both of which regions contribute carriers to the active region. The laser devices disclosed are made, for example, from layers of appropriately doped P and N type gallium arsenide and from layers of P and N type gallium aluminum arsenide. The resulting devices can have very small cavity cross sections, optical and electrical confinement of the excitation at all the side surfaces, low electrical series resistance and a low thermal resistance due to geometrical factors. The laser devices disclosed may be fabricated using well known fabrication techniques which include deposition of the layers of the laser by liquid phase epitaxy (LPE), molecular beam epitaxy (MBE) and melt-back or etching techniques. The latter techniques define the laser cavity.
13 citations
TL;DR: In this paper, a construction of a semiconductor laser with longitudinal pumping which has been called a radiating mirror was proposed and experimentally realized in [1]-[4], using this scheme of excitation one can obtain rather high radiation powers with a good directionality.
Abstract: A construction of a semiconductor laser with longitudinal pumping which has been called a radiating mirror was proposed and experimentally realized in [1]-[4]. Using this scheme of excitation one can obtain rather high radiation powers with a good directionality.
9 citations
TL;DR: In this paper, the authors demonstrate that only a small number of properly selected compositions would be needed to completely cover this spectral region and demonstrate that a large number of correctly selected compositions is sufficient to cover the entire spectral region.
Abstract: Optically pumped lasers operating at 2 K and emitting between 3.9 and 8.6 μm have been produced from PbS x Se 1-x crystals of several alloy compositions. Because the lasers operate with large bandwidths, the results demonstrate that only a small number of properly selected compositions would be needed to completely cover this spectral region.
6 citations
Patent•
IBM1
TL;DR: A double quantum laser employing volatile monoiodides as the active medium and using a combination of stimulated Raman emission and four wave parametric conversion to generate two pulses suitable for triggering the double quantum amplification process is described in this article.
Abstract: A double quantum laser employing volatile monoiodides as the active medium and using a combination of stimulated Raman emission and four wave parametric conversion to generate two pulses suitable for triggering the double quantum amplification process.
5 citations
NEC1
4 citations
TL;DR: The pulse-position modulation technique as applied in the case of a pulsed room-temperature-operated GaAs laser diode for communication purposes can be incorporated in the development of a short-haul point-point-to-point voice communication system using the laser diodes.
Abstract: This paper gives details of the pulse-position modulation technique as applied in the case of a pulsed room-temperature-operated GaAs laser diode for communication purposes. The input analog signal is converted into a digital format and information transmission takes place through the laser pulses occurring at different positions in time. Special care is taken to synchronize the receiver with the transmitter. At the receiver the analog information is reconstructed. The technique can be incorporated in the development of a short-haul point-point-to-point voice communication system using the laser diode.
4 citations
4 citations
TL;DR: In this paper, the optical power densities available in electric CO 2 lasers were analyzed for high values of the vibrational temperature of the ν 3 mode (> 1000 K, and they gave values 25 percent lower than those obtained by the classical gain-saturation formula.
Abstract: Sophisticated numerical calculations have been made of the optical power densities available in electric CO 2 lasers. For high values of the vibrational temperature of the ν 3 mode (> 1000 K), they give values 25 percent lower than those obtained by the classical gain-saturation formula. This oversaturation effect may also exist in other types of lasers.
4 citations
TL;DR: In this article, the authors measured the time-resolved spectra of an internal Q-switching emission of electron-beam-excited GaAs lasers at the rate of 5.63 A/ns at 85 K.
Abstract: Time-resolved spectra of an internal Q -switching emission of electron-beam-excited GaAs lasers were measured. The spectra shifted to longer wavelengths at the rate of 5.63 A/ns at 85 K. Time-resolves spectra of a normal laser emission were also measured to be shifted to longer wavelengths at the rate of about 0.3 A/ns. This remarkable difference of the spectral shifts can be understood if the former shift is caused by the quasi-Fermi level in the conduction band and the latter shift is caused by thermal effects.
TL;DR: In this paper, an analysis of singlemode internally frequency-modulated gas laser oscillation is presented, where the modulation is achieved by variation of the index of refraction of the medium within the cavity.
Abstract: An analysis of single-mode internally frequency-modulated gas laser oscillation is presented. The modulation is achieved by variation of the index of refraction of the medium within the cavity. The analytical treatment follows the Lamb formalism. It is shown that modulation bandwidth is not limited by the cavity bandwidth. Limitations by other factors (e.g., linewidth of the active medium) are not treated.
TL;DR: In this paper, PbS diode lasers have been developed with cw output powers of about 1/3 W in the 4.3μm wavelength region, achieving external quantum efficiencies as high as 27%.
Abstract: Stripe‐geometry PbS diode lasers have been developed with cw output powers of about 1/3 W in the 4.3‐μm wavelength region. A maximum cw output power in a single longitudinal mode of about 50 mW, over‐all external quantum efficiencies as high as 27%, and incremental internal quantum efficiencies near 60% have been observed. The improved performance has been achieved through a number of significant developments in device technology.