Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optics Letters

Evanescent-wave-excited quasi-two-dimensional random lasing

Sushil A. Mujumdar, Hema Ramachandran, Narendra Kumar, Ajay Kumar Sood

Published Aug 25, 2006• 4 citations
Publisher

Abstract

We report on random lasing from a dye-scatterer system directly excited by evanescent modes formed over a dielectric-dielectric interface. The system is quasi-two-dimensional because of the subwavelength exponential decay of the excitation energy. Spectral narrowing by a factor of approximately 13 was obtained under diffusive scattering conditions. The peak intensity exhibited a unique dual-saturation behavior due to the localized nature of the excitation. We observed a reduction of threshold for samples with a higher dye concentration because of a larger excitation-state occupation number within the same interaction volume.

DOI
10.1364/ol.31.002722

Related papers

Two- and Three-Photon Pumped Regular and Random Lasing Behaviors in a Scattering Dye Solution With Suspended Polystyrene Microspheres

Guang S. He

Regular and random lasing properties in a multiphoton active and highly scattering dye solution containing polystyrene microspheres of 366-nm diameter have been experimentally studied. Using 100-fs laser pulses of wavelength 790 nm and 1300 nm as the two- and three-photon excitation sources, the frequency-upconversion regular lasing of ~610 nm wavelength can be generated along both the forward and backward directions, characterized by high directionality, higher spectral intensity, and remarkable spectral narrowing. In the meantime, the random lasing can also be observed along all other directions, characterized by only spectral narrowing but with much lower spectral brightness. The spectral brightness ratio between the forward regular lasing and the random lasing is ($10^{4}$-$10^{5}$):1. Comparing to the input pump beam of ~3 mm diameter and divergence angle of$\theta _{0}~\approx ~0.9$mrad, the forward lasing beam size and divergence angle were ~7 mm and ~(3-4)$\theta _{0}$, whereas the corresponding parameters were ~5 mm and$\sim 1.5~\theta _{0}$for the backward lasing beam, indicating the phase-conjugation property of the latter.

IEEE Journal of Quantum Electronics•Mar 6, 2025•2 citations

Influence of Spatial Localization on Lasing Threshold of Quasi-State Mode in One-Dimension Random Media

Jinsong Liu

Based on the time dependent theory of random lasers, which was built via combining Maxwell equations with the rate equations of a four-level atomic system, the output intensity of a lasing mode varying with the pumping rate is simulated for a two-dimensional random active medium by use of the finite difference time domain method. Results show that the pumping rate dependence of the output intensity presents not only a threshold property, but also a saturation property, just like that of lasing modes in conventional lasers. Charactering the mode's localization extent via the mode's area indicates that the stronger the mode's localization extent is, the lower the mode's threshold is. However, such a relation is not a one-to-one correspondence, meaning that the mode's localization extent is an important fact to determine the mode's threshold, but is not alone.

Optics & Optoelectronic Technology•Jan 1, 2006•0 citations

Lasing in strongly scattering dielectric microstructures

Lucia Florescu

In the first part of this thesis, a detailed analysis of lasing in random multiple-light-scattering media with gain is presented. Random laser emission is analyzed using a time-dependent diffusion model for light propagating in the medium containing active atoms. We demonstrate the effects of scatterers to narrow the emission spectral linewidth and to shorten the emitted pulse duration at a specific threshold pump intensity. This threshold pump intensity decreases with scatterer density and excitation spot diameter, in excellent agreement with experimental results. The coherence properties of the random laser are studied using a generalized master equation. The random laser medium is treated as a collection of low quality-factor cavities, coupled by random photon diffusion. Laser-like coherence, on average, is demonstrated above a specific pumping threshold. We demonstrate that with stronger scattering, the pumping threshold for the transition from chaotic to isotropic coherent light emission decreases and enhanced optical coherence for the emitted light is achieved above threshold. The second part of this thesis presents a study of lasing in photonic crystals (PCs). The emission from an incoherently pumped atomic system in interaction with the electro-magnetic reservoir of a PC is analyzed using a set of generalized semiclassical Maxwell-Bloch equations. We demonstrate that the photonic band edge facilitates the enhancement of stimulated emission and the reduction of internal losses, leading to an important lowering of the laser threshold. In addition, an increase of the laser output at a photonic band edge is demonstrated. We next develop a detailed quantum theory of a coherently pumped two-level atom in a photonic band gap material, coupled to both a multi-mode wave-guide channel and a high-quality micro-cavity embedded within the PC. The cavity field characteristics are highly distinct from that of a corresponding high-Q cavity in ordinary vacuum. We demonstrate enhanced, inversionless, and nearly coherent light generation when the photon density of states (DOS) jump between the Mollow spectral components of atomic resonance fluorescence is large. In the case of a vanishing photon DOS on the lower Mollow sideband and no dipolar dephasing, the emitted photon statistics is Poissonian and the cavity field exhibits quadrature coherence.

•Jan 1, 2004•0 citations

Lasing in a random amplifying medium: Spatiotemporal characteristics and nonadiabatic atomic dynamics

Lucia Florescu, Sajeev John

We study the dynamics of lasing from photonic paints excited by short, localized, optical pulses, using a time-dependent diffusion model for light propagating in the medium containing active atoms. The full time-dependent, nonadiabatic nonlinear response of the atomic system to the local optical field intensity is described using the Einstein rate equations for absorption and emission of light. Solving the time-dependent diffusion equation for the light intensity in the medium with nonlinear gain and loss, we derive detailed information on the spectral, spatial, and temporal properties of the emitted laser light. Our model recaptures the effects of scatterers to narrow the emission spectral linewidth and to narrow the emitted pulse duration, at a specific threshold pump intensity. Our model also describes how this threshold pump intensity decreases with scatterer density and excitation spot diameter, in excellent agreement with experimental results.

Physical Review E•Sep 20, 2004•21 citations

Lasing in active, sub-mean-free path-sized systems with dense, random, weak scatterers

B. Raghavendra Prasad, Hema Ramachandran, Ajay Kumar Sood +2 more

We report enhanced emission and gain narrowing in Rhodamine 590 perchlorate dye in an aqueous suspension of polystyrene microspheres. A systematic experimental study of the threshold condition for and the gain narrowing of the stimulated emission over a wide range of dye concentrations and scatterer number densities showed several interesting features, even though the transport mean free path far exceeded the system size. The conventional diffusive-reactive approximation to radiative transfer in an inhomogeneously illuminated random amplifying medium, which is valid for a transport mean-free path much smaller than the system size, is clearly inapplicable here. We propose a new probabilistic approach for the present case of dense, random, weak scatterers involving the otherwise rare and ignorable sub-mean-free-path scatterings, now made effective by the high gain in the medium, which is consistent with experimentally observed features.

Applied Optics•Oct 20, 1997•39 citations

Spectral and Temporal Emission Behaviors in Disordered Scattering of Rh640 Dye Solution

He‐Zhou Wang, Zhao Fu-li, Huang Xu-guang +3 more

The fluorescent decays and spectra of pump power density dependent emission demonstrated that the excitation power density was enhanced in Rh640 dye solution containing scattering nanoparticles. Lasing in disordered scattering medium with low threshold, narrow bandwidth, and short duration was observed. The mechanism of this enhancement, together with the lasing properties of low threshold and narrow bandwidth, was discussed.

Chinese Physics Letters•Oct 1, 1997•3 citations
We report on random lasing from a dye-scatterer system directly excited by evanescent modes formed over a dielectric-dielectric interface. The system is quasi-two-dimensional because of the subwavelength exponential decay of the excitation energy. Spectral narrowing by a factor of approximately 13 was obtained under diffusive scattering conditions. The peak intensity exhibited a unique dual-saturation behavior due to the localized nature of the excitation. We observed a reduction of threshold for samples with a higher dye concentration because of a larger excitation-state occupation number within the same interaction volume.
Regular and random lasing properties in a multiphoton active and highly scattering dye solution containing polystyrene microspheres of 366-nm diameter have been experimentally studied. Using 100-fs laser pulses of wavelength 790 nm and 1300 nm as the two- and three-photon excitation sources, the frequency-upconversion regular lasing of ~610 nm wavelength can be generated along both the forward and backward directions, characterized by high directionality, higher spectral intensity, and remarkable spectral narrowing. In the meantime, the random lasing can also be observed along all other directions, characterized by only spectral narrowing but with much lower spectral brightness. The spectral brightness ratio between the forward regular lasing and the random lasing is (10410^{4}104-10510^{5}105):1. Comparing to the input pump beam of ~3 mm diameter and divergence angle ofθ0 ≈ 0.9\theta _{0}~\approx ~0.9θ0​ ≈ 0.9mrad, the forward lasing beam size and divergence angle were ~7 mm and ~(3-4)θ0\theta _{0}θ0​, whereas the corresponding parameters were ~5 mm and∼1.5 θ0\sim 1.5~\theta _{0}∼1.5 θ0​for the backward lasing beam, indicating the phase-conjugation property of the latter.
Based on the time dependent theory of random lasers, which was built via combining Maxwell equations with the rate equations of a four-level atomic system, the output intensity of a lasing mode varying with the pumping rate is simulated for a two-dimensional random active medium by use of the finite difference time domain method. Results show that the pumping rate dependence of the output intensity presents not only a threshold property, but also a saturation property, just like that of lasing modes in conventional lasers. Charactering the mode's localization extent via the mode's area indicates that the stronger the mode's localization extent is, the lower the mode's threshold is. However, such a relation is not a one-to-one correspondence, meaning that the mode's localization extent is an important fact to determine the mode's threshold, but is not alone.
In the first part of this thesis, a detailed analysis of lasing in random multiple-light-scattering media with gain is presented. Random laser emission is analyzed using a time-dependent diffusion model for light propagating in the medium containing active atoms. We demonstrate the effects of scatterers to narrow the emission spectral linewidth and to shorten the emitted pulse duration at a specific threshold pump intensity. This threshold pump intensity decreases with scatterer density and excitation spot diameter, in excellent agreement with experimental results. The coherence properties of the random laser are studied using a generalized master equation. The random laser medium is treated as a collection of low quality-factor cavities, coupled by random photon diffusion. Laser-like coherence, on average, is demonstrated above a specific pumping threshold. We demonstrate that with stronger scattering, the pumping threshold for the transition from chaotic to isotropic coherent light emission decreases and enhanced optical coherence for the emitted light is achieved above threshold. The second part of this thesis presents a study of lasing in photonic crystals (PCs). The emission from an incoherently pumped atomic system in interaction with the electro-magnetic reservoir of a PC is analyzed using a set of generalized semiclassical Maxwell-Bloch equations. We demonstrate that the photonic band edge facilitates the enhancement of stimulated emission and the reduction of internal losses, leading to an important lowering of the laser threshold. In addition, an increase of the laser output at a photonic band edge is demonstrated. We next develop a detailed quantum theory of a coherently pumped two-level atom in a photonic band gap material, coupled to both a multi-mode wave-guide channel and a high-quality micro-cavity embedded within the PC. The cavity field characteristics are highly distinct from that of a corresponding high-Q cavity in ordinary vacuum. We demonstrate enhanced, inversionless, and nearly coherent light generation when the photon density of states (DOS) jump between the Mollow spectral components of atomic resonance fluorescence is large. In the case of a vanishing photon DOS on the lower Mollow sideband and no dipolar dephasing, the emitted photon statistics is Poissonian and the cavity field exhibits quadrature coherence.
We study the dynamics of lasing from photonic paints excited by short, localized, optical pulses, using a time-dependent diffusion model for light propagating in the medium containing active atoms. The full time-dependent, nonadiabatic nonlinear response of the atomic system to the local optical field intensity is described using the Einstein rate equations for absorption and emission of light. Solving the time-dependent diffusion equation for the light intensity in the medium with nonlinear gain and loss, we derive detailed information on the spectral, spatial, and temporal properties of the emitted laser light. Our model recaptures the effects of scatterers to narrow the emission spectral linewidth and to narrow the emitted pulse duration, at a specific threshold pump intensity. Our model also describes how this threshold pump intensity decreases with scatterer density and excitation spot diameter, in excellent agreement with experimental results.
We report enhanced emission and gain narrowing in Rhodamine 590 perchlorate dye in an aqueous suspension of polystyrene microspheres. A systematic experimental study of the threshold condition for and the gain narrowing of the stimulated emission over a wide range of dye concentrations and scatterer number densities showed several interesting features, even though the transport mean free path far exceeded the system size. The conventional diffusive-reactive approximation to radiative transfer in an inhomogeneously illuminated random amplifying medium, which is valid for a transport mean-free path much smaller than the system size, is clearly inapplicable here. We propose a new probabilistic approach for the present case of dense, random, weak scatterers involving the otherwise rare and ignorable sub-mean-free-path scatterings, now made effective by the high gain in the medium, which is consistent with experimentally observed features.