68 results about "Leaky mode" patented technology

Lightwave diffraction device formed of a dielectric layer (4), a mirror (12) arranged at the lower face (10) of said layer, a semi-reflective structure (13) arranged at the upper face (100) of said layer, and a diffractive structure (8) arranged in said layer or on its faces. The height (H) of the layer is chosen so as to substantially satisfy the resonance condition for at least one leaky mode propagating in said layer for at least one given incident wave having a determined wavelengthλ and a determined incidence angle θ_c. Next, the diffractive structure is arranged so that there is no propagating positive diffracted order, and so that all negative orders other than the −1^st propagating order have zero or a relatively small diffraction efficiency, the reflected −1^st order propagating in a direction non-parallel to the incident wave. This diffraction device allows a high diffraction efficiency of up to 100% for the −1^st order.

Mechanically tunable electromagnetic and photonic devices featuring enhanced spectral tunability with minimal mechanical movement are provided. These nano/micro-electromechanically (N/MEMS) tunable elements, including filters and pixels, rely on leaky-mode resonance effects in subwavelength photonic lattices that constitute periodic wavelengths. Such elements can operate in reflection (bandstop) or transmission (bandpass) modes, and can be arranged in one-dimensional or two-dimensional arrays, or operated as single units, and their spectral regions are controlled by the element design. Input electromagnetic radiation illuminates the element and is then filtered, modulated, analyzed or tuned by the element. Mechanical motion alters the structural symmetry, and therefore, the tuning properties, of the nanostructured subwavelength resonance elements. Further, incorporating metals and dielectrics to generate coexisting plasmonic and leaky-mode resonance effects adds to the versatility of the potential applications.

Optical devices with versatile spectral attributes are provided that are implemented with one or more modulated and homogeneous layers to realize leaky-mode resonance operation and corresponding versatile spectral-band design. The first and/or higher multiple evanescent diffraction orders are applied to excite one or more leaky modes. The one- or two-dimensional periodic structure, fashioned by proper distribution of materials within each period, can have a resulting symmetric or asymmetric profile to permit a broadened variety of resonant leaky-mode devices to be realized. Thus, the attributes of the optical device permit, among other things, adjacent, distinct resonance frequencies or wavelengths to be produced, convenient shaping of the reflection and transmission spectra for such optical device to be accomplished, and the wavelength resonance locations to be precisely controlled so as to affect the extent to which the leaky modes interact with each other. Further, the profile asymmetry allows for the precise spectral spacing of interactive leaky modes so as to provide greater flexibility in optical device design.

The optical sensor of the present invention detects both the existence and concentration of substances by changing from light leakage mode to wave guide mode when the sensor is exposed to the substances to be detected. The changes in the mode results in a large change in optical output. This change is measured and the substance is identified and/or measured with high sensitivity.The change in light leakage mode to wave guide mode of the sensor is possible by having a clad material around the core material, with the clad material decreasing in the index of refraction when exposed to the substance to be detected. When the index of refraction of the clad becomes less than that of the core material, the sensor changes from the light leakage mode and operates in the wave guide mode. Changes in light intensity output from the sensor is measured over time, and correlated to the substance to be detected.

A light field generator system including a leaky-mode SAW modulator is disclosed. The modulator incorporates at least one optical power component, such as a concave mirror or volume grating having a non-zero diopter rating. In some embodiments, the system incorporates the at least one optical power component by embedding the optical power component within a substrate of the SAW modulator and/or by placing the optical power component upon a surface of the SAW modulator.

A few-mode optical fiber comprises a core surrounded by a cladding, having a step index profile that is structured to support propagation of a plurality of desired signal-carrying modes, while suppressing undesired modes. The core and cladding are configured such that the undesired modes have respective effective indices that are close to, or less than, the cladding index such that the undesired modes are leaky modes. The index spacing between the desired mode having the lowest effective index and the leaky mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween.

A high time-resolution ultrasensitive optical detector, using a planar waveguide leakage mode, and methods for making the detector. The detector includes a stacking with a dielectric substrate, a detection element, first and second dielectric layers, and a dielectric superstrate configured to send photon(s) into the light guide formed by the first layer. The thicknesses of the layers is chosen to enable a resonant coupling between the photon(s) and a leakage mode of the guide, the stacking having an absorption resonance linked to the leakage mode for a given polarization of the photon(s).

A spectroscopic based optical fiber sensor includes a sensitive optical fiber, a probing light source, a power supply, a detector means, a signal processing means, and a display means. The sensitive optical fiber is optically affected by the presence of at least one measurand. The probing light source, adjacent to the sensitive fiber, transversely illuminates the fiber from the outside. The probing light is modified by the sensitive fiber, coupled into the optical fiber core, either as bound modes or leaky modes, as a light signal and guided to a detector means located at the terminus of the optical fiber. The detector means correlates the intensity of the light signal with an electric signal and transmits the electric signal to the signal processing means, wherein the electric signal is correlated to the quantity being measured. The correlated quantity being transmitted and displayed on the display means.

It is proposed a multimode optical fiber including a central core, an inner depressed cladding, a depressed trench, an outer depressed cladding, and an outer cladding. The central core has an alpha-index profile. The depressed claddings limit the impact of leaky modes on optical-fiber performance characteristics (e.g., bandwidth, core size, and/or numerical aperture).

The invention provides a method for inversion of speed of soft formation transverse waves by leaky mode waves, belonging to a logging technology applying physical geophysical sound waves. The specific steps are as follows: inputting wave shape of monopole or dipole leaky mode waves of a soft formation well section with serious diameter extension and conventional well measurement data of corresponding well section formation; extracting a phase velocity dispersion curve of the leaky mode waves from array wave shape and determining the main energy frequency range of the leaky mode waves; at various speeds of formation transverse waves, calculating variance between the leaky mode waves speed calculated by theoretical arithmetic and the leaky mode waves phase velocity extracted from field array wave shape; determining the corresponding formation transverse wave speed in a state in which the variance is zero so as to carry out successive well section processing and output an inversion transverse speed result map. The invention solves the problem of the prior multipole subarray acoustic logging apparatus that the formation transverse wave speed can not be directly measured in the soft formation well sections with ultra-large well diameters, loose superficial layers or serious diameter extension. The method expands the application fields of the borehole acoustic logging technology in oil exploration process and oil development process, and improves the application value of the borehole acoustic logging technology.

An optical device includes an optical waveguide through which light propagates and a micro-resonator structure including an optical sensor. The micro-resonator is configured to resonate at a wavelength of light that may be transmitted through the optical waveguide. When light at that wavelength is transmitted through the optical waveguide, it resonates in the resonator and is detected by the optical sensor to produce an electrical signal. The optical resonator may be a micro-cylinder, disc or ring resonator and may be coupled to the waveguide via evanescent coupling or leaky-mode coupling. Multiple resonators may be implemented proximate to the waveguide to allow multiple wavelengths to be detected. When the waveguide is coupled to a tunable laser, signals provided by the optical sensor may be used to tune the wavelength of the laser.

Electro-holographic light field generator devices comprising surface acoustic wave (SAW) optical modulators are disclosed that employ multiple output couplers. These output couplers might be distributed along waveguides of the SAW modulators, within output coupling regions. Each of these output couplers can be configured for directing an incident leaky mode light at different output angles. In some cases, it may be desirable to employ the output couplers to function as different sub-pixels, to provide light to different viewing directions. The output couplers may be mirrors, volume gratings, chirped gratings, reflection gratings, two dimensional gratings, and/or transmission gratings. The output couplers may be angled so that the coupling output fans for each optical modulator are offset from the waveguide for that optical modulator.

A method for delaying transmitted light. The method may include illuminating a leaky-mode resonant element with light pulses of short duration and sequences of such pulses. The leaky-mode resonant element may include a spatially modulated periodic layer and may be configured so that at least some of the light is transmitted in a delayed manner.

The invention discloses a broadband micro nano two-dimensional multitooth grating trap filter, for the purpose of improving the photoelectric conversion efficiency of a silicon solar film battery. The structure is as follows: gratings periodically changing along two directions are arranged at the upper surface of a silicon active layer, each of the gratings in the two directions has two teeth, and the teeth are non-uniformly distributed in the two directions of the gratings. According to the invention, through adjusting structural dimensions of the micro nano two-dimensional multitooth gratings and positions of the grating teeth, by use of a leaky-mode resonance effect, the device has the advantages of high transmission efficiency, large bandwidth and wide angle spectrum for transverse electric wave (TE wave) and transverse magnetic wave (TM wave) incident light.

A light steeling system and method for diffractive steering of electromagnetic radiation such as visible light is disclosed. Embodiments of the light steering system include leaky-mode SAW modulators as light modulator devices. The SAW modulators preferably include reflective diffractive gratings. The gratings are mounted to/patterned upon an exit face that opposes an exit surface of the SAW modulator, in one example. Steering of light signals emitted from the SAW modulators in these systems can be accomplished by varying wavelength of light signals introduced to the SAW modulators, and/or by varying frequency of RF drive signals applied to the SAW modulators. In addition, light field generators that incorporate SAW modulators of the proposed light steering system within displays of the light field generators are also disclosed.

The invention discloses a method for judging an effective cavity mode of a resonant cavity enhanced photodetector without an upper reflector, which comprises the following steps: designing a structure of the resonant cavity enhanced photodetector without the upper reflector to form a detector sample; growing the designed detector sample, measuring the reflection spectrum of the sample by a spectrometer and marking the leaky modes of a high-reflectivity belt area in the reflection spectrum; editing a simulation program according to the principle of an optical transmission matrix and simulating to obtain a theoretically simulated reflection spectrum which is completely consistent with the designed resonant cavity enhanced photodetector without the upper reflector in terms of structure and layer thickness; adjusting the thickness of each layer of the reflector and the cavity in the simulation program so that the simulated reflection spectrum is always consistent with the reflection spectrum measured by test; then changing the absorption coefficient of an absorption layer in the simulation program and observing the change of each leaky mode in the simulated reflection spectrum, wherein the leaky mode deriving from the resonant cavity mode, namely the cavity mode, does not changes at the same time, so as to judge whether the leaky modes in the reflection spectrum of the resonant cavity enhanced photodetector without the upper reflector are from active area absorption or from the cavity mode.