Extreme laser background suppression for resonance fluorescence in semiconductor nanostructures

Semiconductor nanostrustures are promising candidates for developing single photon technologies. Relevant demonstrations in this field has been carried out by resonantly coupling a laser beam to a quantum emitter. Such challenging measurements require the suppression of laser background by several order of magnitudes. One way to do that is to use cross polarization confocal microscopy. Normally, high quality commercial crossed polarizers allows a laser suppression down to 5 to 6 orders of magnitudes. Surprisingly, when used in combination with a confocal microscope, the extinction ratio is boosted up to 9 order of magnitudes. This unexpected but very welcome enhancement finds its origin in the Imbert-Fedorov effect, now commonly referred to as Spin Hall effect of light, which manifests itself in the reflectivity of a Gaussian laser beam off a mirror. In this presentation, we will discuss in details the physics and optics of such a remarkable effect, which we mapped in details for the first time.