Persistent coherent random lasing using resonant scatterers

Ravitej Uppu,Sushil Mujumdar

doi:10.1364/oe.19.023523

Abstract

We study the frequency behavior of coherent random lasers consisting monodisperse scatterers with single-particle resonances. A three-dimensional photon propagation model is employed to compute the wavelength-sensitive path length distribution of fluorescence photons in this system. We observe that a persistence interval of wavelengths exists for the coherent random lasing modes, corresponding to the Mie resonances of the individual resonant scatterer. Within the interval, characteristic pulse to pulse fluctuations continue to be observed from the system. The gain competition in the random laser suppresses likely coherent modes in other regions of the emission band, thereby reducing the wavelength fluctuations in the random laser. We further illustrate the tunability of this persistence interval by varying the size parameter of the resonant scatterers.

Highlights

Random lasers are unique optical sources that generate narrowband radiation via the interplay of amplification and multiple scattering within a disordered environment [1,2,3,4,5,6,7]
In the case of nonresonant random lasers, the peak wavelength depends on two parameters, the spontaneous emission event and the lifetime of the corresponding extended mode excited by this photon
We study the random laser with resonant scatterers in comparison to that with polydisperse nonresonant scatterers, the latter assumed to have no wavelength sensitivity

Summary

Introduction

Random lasers are unique optical sources that generate narrowband radiation via the interplay of amplification and multiple scattering within a disordered environment [1,2,3,4,5,6,7]. In a coherent random laser based on nonresonant feedback, the spontaneous emission events that excite amplified extended modes decide the lasing wavelength [16]. This implies, and has been demonstrated, that the peak wavelength fluctuates chaotically with every pulse [17]. In the case of nonresonant random lasers, the peak wavelength depends on two parameters, the spontaneous emission event and the lifetime of the corresponding extended mode excited by this photon While the former is hard to control in a multiply scattering environment, the latter parameter offers a possibility of choosing the wavelength of lasing if the lifetime of the mode could somehow be controlled. We propose the exploitation of resonant scatterers as a possible handle on controlling the wavelength fluctuations

System

Results and analysis

Conclusions