Nanophotonic devices, applications and fabrication by nanoimprint lithography.

摘要

This thesis includes the design, fabrication and characterization of novel nanophotonic devices and their applications as well as the development of unique nanofabrication technologies.; A subwavelength resonant grating filter (SRG) is a novel band-stop filter consisting of a layer of subwavelength (in period and depth) surface relief gratings. SRGs are ultra-thin ( 1 mum), narrow band, highly efficient (∼ 100%), tunable, suitable for integration, and can be fabricated using nanoimprint lithography (NIL). By incorporating a SRG into a commercial multimode diode laser, a tunable single mode laser was demonstrated. It operates at 1.5 mum wavelength with a side mode repression ratio (SMSR) of 36 dB and a wavelength tuning range of 7 nm. It does not require strict temperature control as needed by DFB and DBR lasers for a stable lasing wavelength. A SRG was also used to narrow the spectra and stabilize the wavelengths of high power broad area lasers (BAL). The FWHM of a BAL was reduced from several manometers to less than 0.06 nm and the wavelength drift against temperature was lowered by a factor of 40. This is a much simpler approach than using conventional diffraction gratings.; Nanostructured quarter wave plates (QWP) were designed, fabricated and tested at 850 nm wavelength. The QWPs were used to control polarization switching of VCSELs. Optical oscillators based on polarization self-switching VCSEL were demonstrated. A novel, simple, miniature atomic clock based on a VCSEL oscillator was proposed and it is expected to have improved performance and reduced power consumption.; An innovative nanofabrication process was developed to generate highly ordered arrays of nanorings (40 nm radius) over large areas. The narloring arrays have excellent periodicity, are circular and uniform over wafer scale areas. Nanoring arrays have been fabricated in silicon, oxide and metals. Concentric double rings were fabricated and plasmon resonance in gold nanorings was observed at infrared wavelengths.; Also nanofluidic channels measuring 90 nm in cross section and several centimeters in length at a density of 5 x 104 cm -1 were fabricated by NIL. Stretching DNA molecules using these nanochannels was demonstrated.