Mohinder Sharma

SBS threshold for single mode and multimode GRIN fibers in an all fiber configuration

We investigate stimulated Brillouin scattering (SBS) threshold in single mode and multimode fibers in an all fiber network. The pump is a single mode fiber pigtail attached to a diode. We find the theory and experiment agree for both single mode and multimode GRIN fibers. We modify the bulk SBS threshold equation for use with fibers by properly accounting for mode sizes and modal dispersion.

Dynamics of passively Q-switched microchip lasers

Self-pulsing in passively Q-switched microchip lasers is investigated in detail. The typical range of values of the parameters motivates a new analysis of the laser rate equations. We determine basic properties of the laser intensity oscillations such as threshold conditions, repetition rate, pulsewidth, peak power, and pulse energy. We show that these oscillations appear through a quasi-vertical Hopf bifurcation located slightly above the lasing threshold. Our bifurcation results are verified numerically by modeling a microchip laser experiment with Nd:YAG as the gain medium and YAG:Cr as saturable absorber. Our results agree with the experiment to within 10%.

Extraction characteristics of a one dimensional Talbot cavity with stochastic propagation phase

We study the near- and far-fields of a linear array of fiber lasers in an external Talbot cavity. Each emitter has a random optical path difference (OPD) phase due to length and dispersion differences. The individual emitter fields are described by forward and reverse differential equations in the Rigrod approximation with the Talbot cavity coupling all emitters through boundary conditions. We analytically determine the effect of the rms phase on the increase in the threshold, the decrease in the emitter amplitude, and the decrease in the far-field intensity. These results are confirmed numerically by using a Monte Carlo technique for the phase. This leads to a locking probability, a coherence function, and the on-axis intensity as functions of the rms phase. Another issue which we investigate is the cavity performance for inter-cavity and external cavity phasing and find the latter preferable. We also determine the strong coupling limit for the fill factor.

Effects of the binomial photon distribution on the dynamics of two two-level atoms

Abstract The phenomenon of collapse and revival of the atomic coherence of two two-level atoms interacting with a single mode quantized radiation field in the binomial state is studied theoretically. It is shown that the dynamics of the atomic system is quite sensitive to the photon statistics of the field.