Ph.D Thesis

Ph.D StudentNevet Amir
SubjectMicro and Nano Semiconductor Structures for Enhanced
Multiphoton Processes, and their Applications
DepartmentDepartment of Electrical and Computer Engineering
Supervisors PROF. Meir Orenstein


The technological revolutions during the second half of the 20th century changed our every-day life. The engines behind these revolutions were the birth of semiconductor devices and specifically the transistor - introducing miniature computational capabilities, and the progress in optical communication, enabling the formation of the internet. Although optics has been successfully integrated into semiconductors in terms of optical sources, detectors and for exploiting solar energy, it has not yet been able to introduce a practical alternative to electronics for computing and signal processing, as has been pursued over the past two decades in the field of photonics. A possible reason could be that optical interaction between photons is very weak compared to Coulomb interaction between charge carriers. However, this electronic interaction also sets a fundamental limit on their operation speed. Nonlinear optical devices, on the other hand, based on high-order transitions between energy levels, allow ultrafast signal processing, therefore have great potential to overcome the bottle-neck of electronics. Moreover, the weak interaction of photons with the environment makes them more suitable for quantum applications.

This thesis deals with multi-photon processes, rendering them more practical by exploiting nanotechnology and mature semiconductor fabrication techniques for both detectors and emitters. It also presents unique fundamental phenomena as well as novel applications based on these enhanced processes. It specifically focuses on the lowest order of nonlinear interactions - the two-photon processes, meaning the nonlinear optical processes in which an electron transition between real levels occurs by absorbing or emitting a pair of photons. First, we show that two-photon emission process from semiconductors can be enhanced in a new type of Purcell enhancement, using plasmonic nanoantennas. Then, control over two-photon stimulated emissions from two-photon absorption through two-photon transparency to two-photon gain is achieved in specially designed micro-structures using electrical pumping. Pulse compression using two-photon gain is demonstrated. Higher order processes such as three-photon absorption and second-harmonic generation are also discussed and utilized for high-order coherence measurements and a unique type of interference between independent chaotic sources using a sensitive two-photon detector is demonstrated and analyzed. A novel type of 3D tomography based on two-photon detection is presented and analyzed, with superior depth in respect to regular methods and robustness to turbulence. These demonstrations have both possible quantum applications including entanglement and squeezing, as well as classical applications including pulse compression, ultrafast source characterization, and medical imaging.