Microcavity physics and design will be reviewed. Following an overview of applications in quantum optics, communications and biosensing, recent advances in ultra-high-Q research will be presented.

Optical microcavities

We propose a method for three-dimensional microfabrication with photopolymerization stimulated by two-photon absorption with a pulsed infrared laser An experimental system for the microfabrication has been developed with a Ti:sapphire laser whose oscillating wavelength and pulse width are 790 nm and 200 fs, respectively The usefulness of the proposed method has been verified by fabrication of several kinds of microstructure by use of a resin consisting of photoinitiators, urethane acrylate monomers, and urethane acrylate oligomers

Three-dimensional microfabrication with two-photon-absorbed photopolymerization.

A photonic crystal fibre including a plurality of longitudinal holes (220), in which at least some of the holes have a different cross-sectional area in a first region (200) of the fibre, that region having been heat-treated after fabrication of the fibre, from their cross-sectional area in a second region of the fibre (190), wherein the optical properties of the fibre in the heat-treated region (200) are altered by virture of the change in cross-sectional area of holes (230) in that region (200).

Photonic crystal fibres

This work presents the fabrication of biologically inspired artificial compound eyes The artificial ommatidium, like that of an insect's compound eyes, consists of a refractive polymer microlens, a light-guiding polymer cone, and a self-aligned waveguide to collect light with a small angular acceptance The ommatidia are omnidirectionally arranged along a hemispherical polymer dome such that they provide a wide field of view similar to that of a natural compound eye The spherical configuration of the microlenses is accomplished by reconfigurable microtemplating, that is, polymer replication using the deformed elastomer membrane with microlens patterns The formation of polymer waveguides self-aligned with microlenses is also realized by a self-writing process in a photosensitive polymer resin The angular acceptance is directly measured by three-dimensional optical sectioning with a confocal microscope, and the detailed optical characteristics are studied in comparison with a natural compound eye

http://science.sciencemag.org/content/sci/312/5773/557.full.pdf

Biologically inspired artificial compound eyes.

Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

We demonstrate theoretically and experimentally that optical beams are self-focused and self-trapped upon initiating photopolymerization. This unique nonlinear optical phenomenon is dependent on the optical exposure and produces permanent index-of-refraction changes larger than 0.04. The resulting nonlinear wave equation is shown to be nonlocal in time and displays self-trapped solutions only for sufficiently low average optical intensities.

/pdf/self-focusing-and-self-trapping-of-optical-beams-upon-f2xgcmpyw7.pdf

Self-focusing and self-trapping of optical beams upon photopolymerization.

We developed and fabricated an all-fiber add–drop filter by recording a Bragg grating in the waist of an asymmetric mode converter–coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers. The insertion loss of the device was ~0.1 dB. A narrow spectral bandwidth ( 90%) were also demonstrated. In addition, the filter was polarization independent.

/pdf/all-fiber-zero-insertion-loss-add-drop-filter-for-wavelength-wuxhwp6nge.pdf

All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing.

A wavelength selective optical fiber coupler having various applications in the field of optical communications is disclosed. The coupler is composed of dissimilar waveguides in close proximity. A light induced, permanent index of refraction grating is recorded in the coupler waist. The grating filters and transfers energy within a particular range of wavelengths from a first waveguide to a second waveguide. Transversely asymmetric gratings provide an efficient means of energy transfer. The coupler can be used to combine or multiplex a plurality of lasers operating at slightly different wavelengths into a single fiber. Other embodiments such as a dispersion compensator and gain flattening filter are disclosed.

Wavelength selective optical couplers

Optical components, particularly microoptic glass components used in synthesizing birefringence in filter systems based on polarization interferometer techniques, are fabricated using systems and methods which provide accurate frequency periodicity measurements. These measurements are derived from differential delays induced by in-process glass elements between beam components in a polarization interferometer unit and from progressive wavelength scanning across a wavelength band of interest. The consequent sinusoidal output variation has peak to peak spacings which are measured to provide frequency periodicity values from which precise length corrections for the optical elements can be calculated.

System and method for fabricating components of precise optical path length

Optical beams are self‐focused and self‐trapped upon initiating crosslinking in photoresists This nonlinear optical phenomenon is apparent only for low average optical intensities and produces index of refraction changes as large as 004 We propose using the self‐focusing and self‐trapping phenomenon in projection photolithography to enhance the resolution and depth of focus

/pdf/nonlinear-optical-properties-of-photoresists-for-projection-4g6og5shyw.pdf

Anthony S. Kewitsch

Papers

Self-focusing and self-trapping of optical beams upon photopolymerization.

All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing.

Wavelength selective optical couplers

System and method for fabricating components of precise optical path length

Nonlinear optical properties of photoresists for projection lithography