Open-access microcavity : a new platform for the study of interacting exciton-polaritons

There are couple types of semiconductor microcavities. The most general structure type is fabricated using two distributed Bragg reflector (DBR) mirrors attached by a layer of semiconductor, whereas in open microcavity it is separated by a gap of air or vacum. In this device periodically repeating pairs of low and high refractive index semiconductor layes allows to reflect light very efficiently. Lately, interest increased in the use of open microcavities as they allow to investigate light and matter interactions in an alternative and more freely tunnable way. This system allows creating and studying of polaritons (which are quasi-particles created, when photons and excitons couple strongly) in case QWs (quantum wells) are introduced into the microcavity or even making a single photon source, in case a SAW (sound acoustic wave) device will be manufactured on the bottom mirror, which has QWs, successfully. Single photon source is very important in order to develop secure communication and quantum computers. A very welcoming use case of the open cavities is allowing to very effectively investigate vey small amounts of fluids in absorption spectroscopy, as well as development of ultralow-threshold lasers (low threshold appears, because photons spend more time in the cavity, which depends on Q-factor), because of recirculation insmall volume mode, interaction for the same incident power increases as I = P in λ2πnQV, enhanced emitters, tunable microfilters and etc. ([1],[2], [3]). Polaritons also have long propagation distances, which allows to consider using them for optical circuits ([4]). \nThe project aim is to use this optical semiconductor microcavity system, which allows easy cavity tuning into resonance, to investigate various effects in coupled mirrors, achieve polariton blockade and etc. Samples were made by University of Cambridge, University of Oxford and III-IV semiconductor center in Sheffield. In Chapter 2 experiments using planar DBR mirrors inside open cavity are present. For example, Rabi dependence on cavity length and optimum threshold dependence on detuning. Chapter 3 has data collected using top sample containing top concave mirror. Effective mass and coupled concave mirror coupling strength dependence on cavity length are good examples. Chapter 4 contains introduction of new setup design, which works in transmission and not reflectivity mode, and experiments carried on using it, like achievement of a very efficient polariton transfer from LG01 to LG00 mode. Chapter 5 will introduce to experiments which will be carried out in the future. This includes use of Surface Acoustic Waves (SAW), organic materials and etc. \n