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We present a method for synthesizing complex fiber Bragg gratings using femtosecond UV laser pulses and image projection from a small phase mask. Fiber gratings with arbitrary spectral reflectivity can be achieved by stitching short grating segments with proper phases. The relative phase between neighboring sub-gratings is controlled using in situ UV-excited fluorescence monitoring. During the fabrication, we are able to monitor the amplitude and phase of each segment right after it was written. This is accomplished by scanning the phase mask with attenuated UV laser pulses and observing modulation in fluorescence. This information allows us to precisely set the position of fiber for the next segment. A fabricated grating segment can also be effectively erased with additional out-of-phase UV exposure. Bragg gratings over both telecom C-band and L-band can be conveniently achieved with this simple setup and a single phase mask.

MAP was used to fabricate polymer DRRs as its high resolution allows precise control on the coupling/transmission coefficients. Pedestal acrylic DRRs with 33nm FSR and −15dB isolation were fabricated and showed qualitative agreement with simulation results.

Improvement of resolution beyond the Rayleigh limit is obtained by monitoring non-resonant four wave mixing generated by the target in a confocal scanning microscope configuration.

Plasmas with densities \ensuremath{\lesssim}${10}^{22}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and electron temperatures ${\mathit{T}}_{\mathit{e}}$\ensuremath{\lesssim}200 eV were produced near solid graphite targets that were laser irradiated at \ensuremath{\sim}${10}^{15}$ W/${\mathrm{cm}}^{2}$, with a \ensuremath{\sim}${10}^{11}$ W/${\mathrm{cm}}^{2}$ prepulse from amplified spontaneous emission. Photographic spectra taken nearly side-on within \ensuremath{\lesssim}0.1 mm from the target surface show strong H-like lines corresponding to n=2,3, and 4 to n=1 transitions and weaker He-like lines, with full width at half maximum widths \ensuremath{\lesssim}4 eV. The Lyman-\ensuremath{\alpha} line is optically thick. A five-layer model with high-electron-density and electron-temperature core layers and less dense and cooler outer layers was used for simulation. Central layers with high ${\mathit{T}}_{\mathit{e}}$ contribute most of the emission while outside cooler layers cause an absorption dip in the central part of the Lyman-\ensuremath{\alpha} line. Asymmetrical self-reversal is interpreted by radial expansion. A plasma-induced line shift was evident in some of the experimental line profiles, especially for the asymmetrical and strongly shifted Lyman-\ensuremath{\gamma} line of C vi ions. Time-dependent rate equations were solved for checking the assumed local-thermodynamic-equilibrium condition for plasmas with adiabatic expansion cooling.

Micro-ring resonators with good performance were fabricated using multi-photon absorption polymerization (MAP) on PDMS and directly pressed against SPF producing variable resonances in the optical output spectrum depending on positioning and pressure.

Resolution of an optical system for grating detection was improved by a factor of two beyond the Abbe diffraction limit using nonlinear optics. Use of non-classical illumination did not provide any improvement.

In this paper, we report on progress in the fabrication of a high speed optical phase modulator based on a nonlinear electro-optic (EO) polymer with an in-plane slotline radio frequency (RF) electrode structure. Compared to microstrip, a slotline RF electrode design has several potential advantages such as easy fabrication, high poling efficiency, low V π , and suppression of current drift. The guest-host nonlinear polymer system AJL49/APC was used in the device. Design, fabrication, and characterization are presented.

The distribution of excited-state titanium atoms in an argon plasma at atmospheric pressure has been studied by spectroscopic measurements. The upper levels of the argon atoms were found to be in equilibrium with the continuum; electron collisions are dominant for these levels and the Boltzmann temperature compared favorably with the LTE temperature obtained from the extrapolated electron density. The distribution of titanium atoms was found to be far from equilibrium. The temperature determined from the intensity ratios of titanium emission lines differs by a factor of more than two from the electron temperature obtained from argon emission-line data. The titanium data were corrected by using a modified diffusion model. The resulting electron temperature is within 14% of that determined from a Boltzmann plot of the argon emission lines. This study suggests a procedural method to use emission-line data of metal atoms in a low-temperature plasma to obtain a better estimate of the electron temperature and to predict other population densities for situations in which the energy separation of the excited state from the ionization level is sufficiently large so that radiation processes are dominant over excited-state depopulations.

Phase-sensitive amplification of picosecond optical pulses was demonstrated using an SOA as the nonlinear medium inside a Sagnac interferometer. Ratios of maximum to minimum gain of more than 3:1 were experimentally measured. Numerical simulations using a semiconductor amplifier model are consistent with experiments.

Phase-sensitive amplification of picosecond optical pulses was demonstrated using an SOA as the nonlinear medium inside a Sagnac interferometer with a weak control signal. Numerical simulations using a semiconductor amplifier model are consistent with experiments.

Techniques for directly dispensing fluorinated polymer waveguides on printed circuit (PC) boards and for fabricating undercut couplers are presented. The dispensed fluorinated polymer waveguides and undercut couplers provide low loss transmission at 1550 nm.

We review our progress in fabricating polymer optical waveguides using three techniques: laser ablation and automatic dispensing, standard photolithography, and 3D multiphoton absorption polymerization. Applications discussed include optical interconnects for PC boards and microring resonators.

A simple optical arrangement for phase sensitive detection of DFWM to characterize the real and imaginary parts of chi(3) is demonstrated. A processable polyacetylene sample is characterized at a wavelength of 1.5 mu(3)m using this technique.

Optical polymer waveguides were fabricated using a direct-dispensing technique. Grating couplers with deep grooves were fabricated by laser ablation. Optical measurements at a wavelength of 1.55mum gave a grating coupling efficiency close to 50%

Techniques for directly-dispensing of polymer waveguides in laser-ablated trenches on printed circuit (PC) boards and for fabricating grating couplers are presented. The blazed grating couplers on re-shaped waveguide ends provided high coupling efficiency.

We report progress in the development of polymer waveguides and devices for photonic applications in three areas: non-photolithographic techniques for polymer waveguide fabrication, bistability in laterally-coupled polymer microring resonators, and ultrafast photoconductive switches fabricated from semiconducting polymers. The non-photolithographic techniques for waveguide fabrication under development include laser milling with an excimer laser and programmable automatic dispensing of multimode polymer waveguides using an Essemtech automatic dispenser. Asymmetric diffraction gratings fabricated using phase masks and the interference of two excimer laser beams have exhibited concentration of optical power into the 1st diffraction order. Polymer micro-ring resonators laterally coupled to a bus line were fabricated by lithography from benzocyclobutene with radii as small as 10 μm and free spectral ranges on the order of 20 nm. These devices exhibit bistability in the frequency domain which can arise from thermal or nonlinear optical changes in refractive index and that may have application for all-optical switching. Metal-polymer-metal switches fabricated with interdigitated electrodes in an inverted structure exhibited fast transient photoconductive pulsewidths under 20 ps in response to femtosecond pump laser pulses, but the measurement was bandwidth limited by the oscilloscope. Here we report pump-probe measurements that indicate carrier lifetimes on the order of 2 ps.

With the increasing interest in polymer integrated optical devices, techniques for fabrication of polymer waveguides and gratings are of critical importance [1-3]. We are developing direct laser fabrication techniques for this application. The investigation of the device fabrication is carried out using 20 ns, 193 nm ArF and 100 fs Ti:Sapphire lasers. Nearly single-mode straight waveguides and gratings with a sub-micron period were fabricated by laser ablation of polymer films.

Using a simple optical setup to detect and characterize transmission gratings in the far field, we demonstrate that going beyond the diffraction limit is not possible using linear interaction of nonclassical illumination with the target grating. We also confirm that nonlinear optical interactions with the target grating, or with the optical medium around it, do allow improvement in resolution.

Optical interconnects can provide chip-to-chip data communication with much needed bandwidth as processor speed and density keep growing. Optical waveguides and couplers are essential components for implementing optical interconnections. Techniques for directly dispensing polymer waveguides in laser-ablated trenches on printed circuit boards and for fabricating optical couplers are presented for quick prototype of optical interconnects. High-quality UV curable polymer waveguides were routinely fabricated. High-efficiency couplers, blazed grating couplers on sloped waveguides, sloped facet metal film couplers, and reflective-undercut facet couplers can be fabricated by using excimer laser ablation.

A high-contrast optical switch for imaging partially coherent light (∼150 times the diffraction limit) requires that it have a large angular acceptance. We describe the development of a high-speed Pockels cell that uses a thin crystal to simultaneously achieve high-contrast (greater than 1800:1) and large-angular acceptance (greater than 7 mrad for a 5-mm aperture). A KD*P crystal was used in a longitudinal-mode configuration with plasma discharges forming low-resistance, high optical transmission electrodes to couple the switching voltage. Rise times of the switched optical pulse of the order of 500 ps were observed. Characterization of the device in the near and far fields was also performed.