Physics

Dr. Sushil Mujumdar
TIFR, Mumbai

For a long time, investigations of light transport in disordered media retraced the trail of mesoscopic studies in electronic systems, punctuated by observations such as light diffusion and the metal-insulator transition for light. The addition of optical gain into the disordered medium, however, led to a series of unexpected observations that initiated an idea of optical materials titled, rather fancifully, 'random lasers'. 
In this talk, I will first explain the term random lasers, and then present a report of our own contributions in frequency and intensity statistics thereof. The former study has revealed unknown facets of bandedge and bandgap state lasing[1], and has led to the observation of Anderson localization with gain and the lifetime statistics of Anderson modes. The latter study provided evidence of the manifestation of an exotic statistical process called the truncated Levy flight in random lasers, which enabled us to completely describe the intensity behavior on a single unique platform[2]. Subsequently, we have also identified the role of extreme events in the process, and have resorted to extremal statistics to maximize the efficiency of random lasers.

[1] A K Tiwari and S Mujumdar, Physical Review Letters, 111, 233903 (2013)
[2] R Uppu and S Mujumdar, Physical Review Letters, 114, 183903 (2015)