A study of Absorption and Spatial Hole Burning in Laser action (original) (raw)

Microscopic model of semiconductor laser without inversion

Physical Review A, 2001

From a microscopic set of equations which takes into account spontaneous emission into lasing mode, we derive a macroscopic quantum model of low-threshold semiconductor lasers that includes the parabolic band structure, Pauli blocking of the injection current, and the carrier distribution dependence on the temperature. This model confirms the predictions of lasing without inversion and inversionless intensity squeezing, that were previously made by Yamamoto and co-authors on the basis of a semiclassical two-level approach. In addition, our analysis demonstrates the existence of an optimum temperature value that minimizes the injection current necessary to obtain lasing and intensity squeezing.

Spatial Hole Burning And Its Analogy With Some Non-Physics Context

Abstract The semi classical theory of laser as developed by Willis Lamb and coworkers several decades ago explains a large number of laser phenomena particularly in gaseous phase. In this theory it has been shown that, whenever we plot normalized population difference versus axial coordinates, there appears dips or holes at regular intervals at particular positions along the laser axis. These holes represent the depletion of population inversion thereby meaning the reduction of laser beam intensity. These holes are known as spatial holes. These holes are always present in laser originating from a Fabry-Perot cavity and are not welcome in the operation of high power laser. In the present work, we analyzed the phenomenon of spatial hole burning in the light of some non-physics context.Abstract The semi classical theory of laser as developed by Willis Lamb and coworkers several decades ago explains a large number of laser phenomena particularly in gaseous phase. In this theory it has been shown that, whenever we plot normalized population difference versus axial coordinates, there appears dips or holes at regular intervals at particular positions along the laser axis. These holes represent the depletion of population inversion thereby meaning the reduction of laser beam intensity. These holes are known as spatial holes. These holes are always present in laser originating from a Fabry-Perot cavity and are not welcome in the operation of high power laser. In the present work, we analyzed the phenomenon of spatial hole burning in the light of some non-physics context.

Semiclassical study of the laser transition

Physical Review A, 1997

A semiclassical, nonlinear theory of a single-mode laser is developed so that the transition around threshold can be studied. The field is expressed in the frequency domain which allows us to emphasize the role of the Fabry-Pérot cavity. A generalized Airy function is obtained for the laser line shape: it contains the source line shape and the empty cavity line shape. It describes the laser both above and below threshold, including the transition region where there is an abrupt increase of intensity and decrease of the laser linewidth. The general arguments are illustrated by detailed numerical calculations for the 3.39-m line of the He-Ne laser. The intensity of the spontaneous emission source which plays a central role is computed from first principles.

Spatial hole burning in a quantum dot laser [3625-35]

Detailed theoretical analysis of the longitudinal spatial hole burning in quantum dot (QD) lasers is given. The multimode generation threshold is calculated as a function of the parameters of structure (surface density of QDs, Q D size dispersion, and cavity length) and temperature. Unlike conventional semiconductor lasers, thermally excited escapes of carriers away from QDs, rather than diffusion, are shown to control smoothing-out spatially nonuniform population inversion and hence the multimode generation threshold in QD lasers. A decrease in the QD size dispersion is shown to increase considerably the relative multimode generation threshold. The maximum tolerable QD size dispersion and the minimum tolerable cavity length, at which the lasing is possible to attain, are shown to exist. Concurrent with the decrease of threshold current, the reduction of multimode generation threshold is shown to occur with decreased temperature. For the structures optimized to minimize the threshold current density for the main longitudinal mode, the dependences of the multimode generation threshold on the QD size dispersion, cavity length, and temperature are obtained. The ways to optimizing the QD laser structure, aimed at maximizing the multimo de generation threshold , are outlined.

Quantum theory of a thresholdless laser

Physical Review A, 1999

We develop a quantum theory of a single-mode thresholdless laser. We start from basic Heisenberg-Langevin equations of motion for the field and atomic operators, and obtain an approximate analytical solution to these operator equations. We compare the predictions of this model for the intensity and power spectrum of the field to the results of a Monte Carlo numerical simulation of the original Heisenberg-Langevin equations, and find them in excellent agreement. We also compare these predictions to those of a rate-equation model, which takes into account spontaneous emission. We show that our model gives more reliable results in the bad cavity limit at high intensities. Based upon these results, we propose a simple characterization of the thresholdless behavior. Finally, we apply our model to microsphere Nd-doped lasers at low temperatures, which are promising devices for a well-controlled thresholdless operation. ͓S1050-2947͑99͒10502-X͔

Spatial hole-burning effects in the amplified-spontaneous-emission spectrum of the nonlasing supermode in semiconductor laser arrays

Journal of the Optical Society of America B, 1999

The amplified spontaneous emission spectrum of the light field in the nonlasing supermode of two coupled semiconductor lasers is analyzed using linearized Langevin equations. It is shown that the interference between the laser mode and the fluctuating light field in the non-lasing mode causes spatial holeburning. This effect introduces a phase sensitive coupling between the laser field and the fluctuations of the non-lasing mode. For high laser fields, this coupling splits the spectrum of the non-lasing mode into a triplet consisting of two relaxation oscillation sidebands which are in phase with the laser light and a center line at the lasing frequency with a phase shift of ±π/2 relative to the laser light. As the laser intensity is increased close to threshold, the spectrum shows a continuous transition from the single amplified spontaneous emission line at the frequency of the non-lasing mode to the triplet structure. An analytical expression for this transition is derived and typical features are discussed.

Longitudinal spatial hole burning in a quantum-dot laser

IEEE Journal of Quantum Electronics, 2000

A Mechanistic Reading of Quantum Laser Theory

The Frontiers Collection, 2015

I want to show that the quantum theory of laser radiation provides a good example of a mechanistic explanation in a quantum physical setting. Although the physical concepts and analytical strategies I will outline in the following do admittedly go somewhat beyond high school knowledge, I think it worth going some way into the state-of-the-art treatment of the laser, rather than remaining at a superficial pictorial level. In the course of the ensuing exposition of laser theory, I want to show that the basic equations and the methods for solving them can, despite their initially inaccessible appearance, be closely matched to mechanistic ideas at every stage.

A study of Absorption and Spatial Hole Burning in Laser action (original) (raw)

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