What are the random lasers ?

More Sumit Mishra's questions See All

Is there any tutorials (examples ) available to learn or run mvapack package for metabolites study ?

how is mvapack package more suitable for metabolites ?

06 July 2016 9,252 0 View

What are the methods to confirm a laser beam has a continuous or pulsed nature ?

by seeing naked eye can we think, what is the behavior of laser beam ?

11 December 2015 783 12 View

Why we need Green function in electrodynamics ?

by using Green function , the problems become easier or complicated ? what are the applications to use this Green function ?

09 October 2015 431 4 View

What are the fundamental differences in classical electrodynamics and quantum electrodynamics ?

how we can correlate them ?

08 September 2015 7,836 8 View

Is it possible to achieve population inversion when you have no cavity in laser system?

I want to ask about random lasers in which there is no cavity, so how we can achieve population inversion for lasing action ?

08 September 2015 4,639 12 View

We have three level and four level laser systems. why we don't have five level or more level laser system ?

is it possible to make a laser which have lasing transition in between 4 to 3 level or 5 to 4 level ?

07 August 2015 9,096 1 View

Why are s to s transitions allowed in He-Ne laser ?

As the atomic selection rules says that s to s transitions are not allowed i.e. there must be a change of the angular momentum ?

04 May 2015 6,347 5 View

We have a mirror. How can we identify which are the coated and uncoated sides by using a laser ?

When we shine a laser beam to the both side of the mirror (silver coated and uncoated), I am not getting fringes. How can we recognise both the surfaces? Is there any problem with my technique ?

04 May 2015 7,010 18 View

What are the differences between femtosecond, picosecond, nanosecond and millisecond laser ablation ?

03 April 2015 3,168 6 View

Why we need to generate femto and attosecond laser pulses (as we have nano and microsecond order pulses) ?

what are their (femto, pico second pulses ) advantages over nano pulses.

03 April 2015 1,996 6 View

error in running a model in Abaqus

Excessive rotation of nodes in node set ErrNodeExcessRotation-Step1

17 August 2021 0 0 View

error in modelling model in Abaqus

Excessive rotation of nodes in node set ErrNodeExcessRotation-Step1

17 August 2021 0 0 View

MD MOE RMSD

How to calculate the RMSD values for a MD simulation using MOE?

07 August 2021 0 0 View

MD MOE RMSD

How to calculate the RMSD values for a MD simulation using MOE?

07 August 2021 0 0 View

MGL tools

20 June 2021 0 0 View

fatal error

When I tried to energy minimization my system, I got fatal error as below. Fatal error: Atomtype opls_116 not found Although I've already added this line: ; include water #include "oplsaa.ff/spc.itp" to [molecultype] directive in my topology.

16 June 2021 0 0 View

fatal error

16 June 2021 0 0 View

fatal error

16 June 2021 0 0 View

fatal error

16 June 2021 0 0 View

i have some problem with chtMultiRegionSimpleFoam

--> FOAM FATAL ERROR: Maximum number of iterations exceeded From function Foam::scalar Foam::species::thermo::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo::*)(Foam::scalar) const) const [with Thermo = Foam::hConstThermo >; Type = Foam::sensibleEnthalpy; Foam::scalar = double; Foam::species::thermo = Foam::species::thermo >, Foam::sensibleEnthalpy>] in file /home/ubuntu/OpenFOAM/OpenFOAM-4.1/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 66. FOAM aborting #0 Foam::error::printStack(Foam::Ostream&) at ??:? #1 Foam::error::abort() at ??:? #2 Foam::heRhoThermo >, Foam::sensibleEnthalpy> > > >::calculate() at ??:? #3 Foam::heRhoThermo >, Foam::sensibleEnthalpy> > > >::correct() at ??:? #4 ? at ??:? #5 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #6 ? at ??:?

24 March 2021 0 0 View

Sumit Mishra

what is mean by highly disordered gain medium ? if there is no optical cavity then how population inversion can be achieved ?

Antonio Consoli

A dye solution with scattering particles is an example of a highly disordered gain medium. In general , RLs consist of an active material embedded with highly scattering particles randomly distributed into the same gain material. The device size in this case is set by the pump beam, we can call this the cavity, as in this spatial region were gain is available thanks to the pump, we have amplified spontaneous emission and the feedback for lasing is given my multiple scattering. However you have to consider that we are dealing with a distributed feedback device (as DFB lasers) so that the concept of cavity must be taken in this context. In RLs, the spatial distribution of refreactive index is not periodic (as in DFB) but random.

Now, if we build a RL in which gain and feedback are spatially separated we can obtain a device with same properties. We have done this by enclosing the material gain (with no scatterers) between two rough walls of scattering particles. This is equivalent to a FP laser with scattering reflectors instead of mirrors. In the attached publication, we report experimental results and theoretical explanation. Hope this could help. Comments and suggestions are sincerely welcome.

Article Decoupling gain and feedback in coherent random lasers: Expe...