Emission Characteristics Of Lasers Research Articles

Injection quantum-well laser with external optical feedback

An investigation was made of the influence of the parameters of an external optical feedback loop and of the pump current on the emission characteristics of injection quantum-well lasers and of lasers with a conventional three-dimensional active region. Five lasing regimes were observed. The critical feedback, at which a strong noise was observed and a catastrophic broadening of the lasing line took place, was found to rise rapidly on reduction in the length of the external resonator. The spectrum of the noise generated by the external feedback loop could be divided into hf and lf components, with characteristic frequencies governed by the length of the external resonator, as well as a very-low-frequency component with the spectrum of the ν −ρ type (where ρ = 2) due to random hopping of the external resonator modes.

Coherence and focusing properties of unstable resonator semiconductor lasers

The emission characteristics of unstable resonator semiconductor lasers were measured. The output of an 80-μm-wide laser consists of a diverging beam with a virtual source 5 μm wide located 50 μm behind the laser facet. A high degree of spatial coherence of the laser output was measured, indicating single lateral mode operation for currents I≲3 Ith.

Control of the emission characteristics of dye ring lasers by phase-polarization resonance methods

Narrowing of the emission spectrum of a dye laser from 10--15 nm to a value smaller than the width of an atomic absorption line was achieved. A single emission line locked to the center of the absorption profile was observed for one direction of propagation in the ring resonator, whereas in the opposite direction there were two lines locked to two parts of the absorption profile located symmetrically relative to its center. The ''hard'' regime of excitation of stimulated emission was possible in the investigated laser.

Influence of active-medium inhomogeneities on the single-pulse emission characteristics of periodic lasers with unstable resonators

A study is made of the influence of a lens-like active medium, and of optical inhomogeneities induced in it, on the spatial and temporal characteristics of single-pulse emission from a solid-state laser having unstable resonators. The analysis is performed by numerically solving the integral equation for an open resonator, filled with an active thermally deformed medium. The real active-medium temperature distribution is taken into account in calculating the equivalent resonator instability and the effective gain over the cross section of the active medium and in analyzing the features of spectrum formation and of the angular distribution of the emitted radiation.

Relationship between the emission characteristics of lasers and flashlamps over extended operation

Relationship between the emission characteristics of lasers and flashlamps over extended operation

Investigation of degradation of electron-beam-pumped cadmium sulfide lasers

An investigation was made of the degradation effects of the emitted radiation and of 50 keV electron-beam pumping on the emission characteristics of CdS lasers. Catastrophic and gradual degradation processes in CdS crystals were studied. An analysis was made of the mechanism of charging of the impurity centers, which was responsible for the instability of the output power, and of the ''potential displacement'' of sulfur atoms from regular sites in the CdS lattice, which reduced the internal quantum efficiency.

Light emission and electrical characteristics of epitaxial GaAs lasers and tunnel diodes

Lasing characteristics of epitaxially formed GaAs p-n junctions are compared with those of Zn diffused lasers. Abrupt epitaxially formed junctions only lased when a high concentration of donors was deliberately added to the p-type side. This result supports Nelson's et al. band filling model of the GaAs laser and relates the impurity band in this model to the n-type dopant.