M.Sc Thesis

M.Sc StudentBen-Aroya Ido
SubjectNarrow Atomic Resonance Based on Coherent Population
Trapping in Rubidium Driven by a Directly
Modulated Laser Diode
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Gad Eisenstein


Coherent Population Trapping (CPT) is a quantum phenomenon which occurs while two coherent electromagnetic fields interact with a three-level atomic system. This unique atom-fields interaction leads to a dramatic change in the absorption profile of the atomic medium and theoretically causes to a complete cancellation of the absorption even though both fields are in resonance with the atomic system (Electromagnetically Induced Transparency or EIT). The CPT resonance, which is known also as the “Dark resonance”, can provide an ultra-narrow linewidths (few dozens of Hertz were already demonstrated) around a fixed frequency (RF region) dictated by the atomic system configuration.


This thesis reports on a design and a setup of an "all-optical" apparatus for observing CPT in 87Rb atoms while using a directly modulated laser diode as the source for the two coherent phase matched fields. The optical spectrum of a directly modulated laser diode (VCSEL) is very complicated due to non linear effects. When it interacts with the atomic medium, a complicated absorption spectrum is generated. This spectrum has to be analyzed in detail in order to obtain CPT. A detailed analysis of the spectrum is presented and a CPT resonance with a linewidth of approximately 1.3kHz is demonstrated.