The development of a theory four-wave mixing in photo-refractive crystals is described. This solved the undepleted pumps approximation with linear absorption and without using for negligible absorption. Both transmission reflection gratings are treated individually. results used to analyze several photorefractive phase conjugate mirrors, yielding reflectivities thresholds. use as optical distortion correction elements experimental demonstrations passive mirrors

We report here the demonstration of several new optical oscillator configurations including a unidirectional ring and self-pumped phase conjugate mirror. The gain medium is BaTiO3, pumped by 632.8-nm He-Ne laser at power levels down to 50 μW.

We report the application of four-wave mixing to real-time image processing. constructed a nonlinear optical processor using photorefractive medium Bi12SiO20 and demonstrated that it is capable convolving correlating objects with spatial information.

A theory of phase conjugation in asymmetric materials that allow a shift between the grating and light-interference pattern is developed. We find when this nonzero, maximum phase-conjugate reflectivity occurs for unequal pump intensities. The conditions self-oscillation are studied.

Nickel inverse opals with controlled metal filling fraction are fabricated through a combination of colloidal crystal templated electrodeposition and electropolishing (see figure). Optical measurements demonstrate that both reflection emission significantly modified by the photonic structure. The optical properties truly three dimensional only at low fractions (after electropolishing).

This paper describes a new type of plasmonic sensor fabricated by imprint lithography using soft, elastomeric mold. Angle-dependent, zero-order transmission experiments demonstrate the sensing potential this device, which uses two dimensional crystal. Full angle-dependent mapping shows that sensitivity to surface chemical binding events reaches maxima near regions Brillouin zone where dispersion curves multiple plasmon polariton modes converge. behavior, together with simple, low cost...

An exact solution of a nonlinear model holographic four-wave mixing is derived. expression for the reflectivity phase-conjugate mirror with depleted pumps presented. We find that such may exhibit bistability.

A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated mirrors it generates only one of its pumping beams by nonlinear interactions, the other being provided feedback probe after transmission through medium. The results a theory yielding reflectivity and oscillation thresholds are presented together with experimental demonstration conjugation barium titanate strontium niobate. device self-starting mixing, has...

We report the results of a theoretical and experimental investigation passive (self-pumped) phase conjugate mirror. This device is based on real time holography in materials which allow spatial shift between refractive index grating light interference pattern. An imaging experiment reported showing conjugating nature device. The holographic medium used was single crystal barium titanate.

Three-dimensional photonic crystals based on macroporous silicon are fabricated by photoelectrochemical etching and subsequent focused-ion-beam drilling. Reflection measurements show a high reflection in the range of stopgap indicate spectral position complete band gap. The onset diffraction which might influence measurement is discussed.

We report the use of Sr1−x Bax Nb2O6 as an efficient holographic four-wave mixing medium. have used this material in a continuous wave phase conjugate mirror with reflectivity exceeding unity, and resonator.

We report here a novel laser resonator with the ability to correct for intracavity phase distortions. The optical cavity employs passive (self-pumped) conjugate reflector provide this capability.

This paper describes a simple technique for fabricating complex, but well defined, three-dimensional (3D) networks of nanoscale flow paths in the channels microfluidic systems. Near field scanning optical measurements reveal optics associated with fabrication process and key features that enable its application to area microfluidics. Confocal studies devices incorporate 3D nanostructures formed using this approach show they function as efficient passive mixing elements, particularly at low...

The output of high power fiber amplifiers is typically limited by stimulated Brillouin scattering (SBS).An analysis SBS with a chirped pump laser indicates that chirp 2.5 × 10 15 Hz/s could raise, an order magnitude, the threshold 20-m fiber.A diode constant and linear 5 has been previously demonstrated.In low-power proof-of-concept experiment, for in 6-km increased factor 100 14 Hz/s.A will enable straightforward coherent combination multiple amplifiers, electronic compensation path length...

We propose using piecewise parabolic phase modulation of the seed laser for suppressing stimulated Brillouin scattering (SBS) in a fiber amplifier. Simulations are run with 9 m passive fiber. Compared random and 0-π pseudo-random modulation, waveform yields higher SBS threshold per unit bandwidth. If bandwidth is defined as range frequencies containing 85% total power, 1.4 times than five- or seven-bit format. more tightly, e.g., 95% three higher. For both cases, achieving 1.5 GHz requires...

Infrared-visible sum frequency generation spectroscopy is used to investigate the corrosion inhibitor benzotriazole (BTAH) adsorbed on Cu(100) and Cu(111) in acidic solution. Potential-dependent situ spectra indicate that molecule anion (BTA-) at all potentials investigated. The surface shown form an ordered adlayer probed, while face be disordered negative potentials, but order with applied positive potential. consist of BTA- two configurations, one coordinated Cu+ ions solution other only...

Recent experimental investigations of the electrodynamic properties high-temperature superconductors in terahertz regime are reviewed. Transmission measurements were performed with use coherent pulse spectroscopy, which enables us to extract directly frequency-dependent complex conductivity σ1+iσ2. Investigations both pure YBa2Cu3O7-δ and related alloy Y1-xPrxBa2Cu3O7-δ conducted over a temperature range from 300 K down 10 K. From these we can temperature-dependent London penetration depth...

We demonstrate one-way optical field imaging through a distorting medium using four-wave mixing implementation of real-time holography. Information can be transmitted at an arbitrarily fast rate as long the respond to changes in distortion.

We propose, analyze and demonstrate the optoelectronic phase-locking of optical waves whose frequencies are chirped continuously rapidly with time. The derived from a common swept-frequency laser based on semiconductor in negative feedback loop, precisely linear frequency chirp 400 GHz 2 ms. In contrast to monochromatic waves, differential delay between two linearly results mutual difference, an acoustooptic shifter is therefore used phase-lock waves. characterize homodyne heterodyne...

Spatially and spectrally resolved photoluminescence (PL) from InGaN/GaN quantum wells is obtained using near-field scanning optical microscopy (NSOM). Samples displaying high macroscopic PL intensity revealed nonuniform linewidth but nearly uniform peak position. It suggests that the contrast in NSOM image reflects distribution of dislocations or defects which act as nonradiative recombination centers. The formation dots with size 30±25 nm their size-dependent interaction were observed...

Photoluminescence, Raman, and Hall measurements are reported for Mg doped GaN films grown by molecular beam epitaxy. The compressive tensile stress determined the Raman shift of phonon lines is due to growth conditions rather than presence in film. photoluminescence peak near band-to-band transitions also shifted larger (smaller) energies (tensile) stress. study longitudinal optical A1 branch shows that its line shape affected mostly crystalline quality

A four-level, plane wave model is proposed for a resonantly pumped 1.6 μm Er3+ laser, including the effect of upconversion. mean population approximation leads to analytical expressions threshold and slope efficiency that are highly accurate compared numerical solution. Using beam area as an adjustable parameter, agree well with data obtained using 1% Er:YAG crystal, at 1470 nm, lasing 1617 in range 0-100°C. According this versus absorbed pump power unaffected by upconversion, but increased...

We measure the transmission of THz pulses through thin films YBCO at temperatures between 10K and 300K. The possess a useable bandwidth extending from 0.1 -- 1.5 (3.3 cm^-1 50 cm^-1). Below T_c we observe pulse reshaping caused by kinetic inductance superconducting charge carriers. From data, extract values London penetration depth as function temperature, find that it agrees well with functional form (\lambda(0)/\lambda(T))^2 = 1 - (T/T_c)^{\alpha}, where \lambda(0) 148 nm, \alpha 2....

A solid immersion lens based on diffraction (dSIL) is proposed as an alternative to the conventional design refraction. analogous a Fresnel zone plate derived in accordance with Huygens–Fresnel principle. Fabrication of binary dSIL achieved by electron-beam lithography and reactive-ion etching LaSF35, index n=2.014. Measurement point-spread function performed near-field optical microscopy. The results are accord expected resolution enhancement factor n respect limit.