טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentBarak Assaf
SubjectNonlinear Dynamics in Optics
DepartmentDepartment of Physics
Supervisor ? 18? Mordechai Segev
Full Thesis textFull thesis text - English Version


Abstract

This dissertation deals with linear and nonlinear optical effects in classic and quantum systems.

1.    Soliton tunneling and ejection from trap potential

Linear tunneling is a characteristic feature of wave-dynamics, manifesting itself in many fascinating ways. Solitons, on the other hand, are nonlinear creatures, whose existence stems from nonlinear waves. Basically, these two phenomena seem unrelated, since their nature is fundamentally different. However, we showed that tunneling in a nonlinear medium may result in a variety of complex dynamical processes. As light power increases we observe transition from linear tunneling of soliton to soliton ejection from a trapping potential.

2.    Autoresonance in Optics   

Autoresonance is a nonlinear phase-locking mechanism that was never addressed before in optics, in spite of the importance of phase-locking for many applications in photonics. We have studied for the first time autoresonance dynamics in optics. We showed that in a chirped directional-coupler aurtoresonance can result in unidirectional power flow between the waveguides for both coherent and incoherent light. We also studied autoresonance of a discrete state coupled to a finite continuum in the non-Markovian regime and showed that phase locking may occur above a collective threshold, and yield efficient amplification of the continuum modes.

3.    Nonclassical Dispersion

One of the interesting results from quantum optics theory is dispersion cancellation. When a biphoton [path-entangled photons] passes through a dispersive medium, the standard quantum optics interference experiments for measuring the wavepacket profile using coincidence count experiments are not affected by the dispersion. We suggested and implemented a method for measuring the dispersion effect on the biphoton. This allowed us to measure new effects of dispersion on biphotons that were never studied before (nonclassical Gouy phase and classical dispersion cancellation).

4.    Single Photon Self-Localization

We study theoretically the evolution of a single photon in array of coupled cavities containing two level atoms. While effective theories that introduce Kerr nonlinearity into the Hamiltonian do not change the dispersion of a single photon wavepacket at all, the system we suggest slows down dramatically the dispersion of a single photon, and results in long life time of the photon. We show that under appropriate conditions the light-matter interaction results in spatial localization of the photon over long times. We also find localized structures of higher number of photons, which are non-separable and non-classical. We show that their existence results from effective nonlinearity that arises from their non-separability.