We first investigate the microscopic working principle of the nanowire superconducting single-photon detectors (SSPDs), and we find that the edge of the nanowire is much more sensitive than the... Show moreWe first investigate the microscopic working principle of the nanowire superconducting single-photon detectors (SSPDs), and we find that the edge of the nanowire is much more sensitive than the central part. The experimental results agree quantitatively with the theory based on a photon-assisted vertex- entry model. We then explore its potential to be used as a probe for near-field detection. Our calculations show that the SSPDs have a much higher signal collection efficiency than the conventional near-field optical microscopy, and that their spacial resolution can reach 20 nm. With photon number resolving ability, a SSPD fabricated on a micro-pillar can be used to investigate the quantum information of the optical near-field at subwavelength scales. Show less
This thesis describes coupling of light to periodic structures. A material is patterned with a regular pattern on a length scale comparable to the wavelength of light. With these structures, light... Show moreThis thesis describes coupling of light to periodic structures. A material is patterned with a regular pattern on a length scale comparable to the wavelength of light. With these structures, light can be manipulated very precisely. The structures find applications in semiconductor lasers, light emitting diodes (LEDs), photovoltaic cells, and detectors of light. A periodic array of holes in a layer of semiconductor or in a thin metal film causes a coupling between the incident light and light that is trapped inside the layer. This coupling can be studied by measuring the reflection and transmission. The environment has an important role here; e.g. placing glass antennas in the holes can increase the coupling between light and plasmons. A thin, superconducting wire can be used as a detector of light. To increase the surface area, the wire is folded into a meander. The optical properties of this detector are very dependent on the polarization, due to the regular periodic structure of the meander. Moreover, we found that the absorption of a very thin absorbing layer can be almost 100%, when it is illuminated under the right angle, from the substrate. This can be used to increase the efficiency of the detectors. Show less