Abstract: Utilization efficiency of cladding pump light in a cladding pumped optical device is improved by converting higher order modes travelling in the cladding to lower order modes that enter the core region and participate more effectively in the energy exchange process. The mode conversion is achieved by asymmetric perturbations in the optical fiber. The perturbations are preferably produced by making the optical fiber in the gain section of the device cylindrically asymmetric. The asymmetric perturbations can be chosen so that they have negligible effect on the lower mode signal light in the core of the optical fiber.

Abstract: An optical microresonator is configured as an optical microbubble formed along a section of an optical microcapillary. The curvature of the outer surface of the microbubble creates an optical resonator with a geometry that encourages the circulating WGMs to remain confined in the central region of the bubble, creating a high Q optical resonator. The resonator may be tuned by modifying the physical properties of the microbubble, allowing the resonator to be used as an optical filter. The resonator may also be used as a sensor or laser by introducing the material to be sensed (or the active laser material) into the microcapillary along which the microbubble is formed.

Abstract: An optical delay line is formed from a coil of optical fiber (in many cases microfiber), where the radius of the optical fiber is greater than the wavelength ? of the propagating signal and the radius R of the coil is selected, in consideration with the optical fiber radius, to limit propagation loss by minimizing coupling between adjacent turns of the coil. The difference in dimension between the fiber diameter and wavelength prevents the mode propagating along one turn from coupling into an adjacent turn. It has been discovered that the modal intensity at the interface between the central rod and the coil will be minimized when the radius of the fiber satisfies the following condition: r >> ( R ? 2 ) 1 / 3 , where ?=(2?n)/?, and n is the refractive index of the fiber.

Abstract: An optical fiber coupler is formed of a section of optical fiber that is positioned between a conventional input fiber (for example, a single mode fiber) or waveguide and a coiled optical fiber device. The adiabatic coupler is coiled (or, at least, curved) to assist in transforming a conventional fundamental mode optical signal propagating along the longitudinal axis of the input fiber to an optical signal that is shifted into a peripheral region of the coiled optical fiber. Moreover, the pitch of an inventive coiled optical fiber coupler can be controlled to assist in the adiabatic transformation process.

Abstract: An optical resonator is configured for optimized performance as a sensor by maximizing the slope and/or sharpness of the resonance peak, instead of maximizing the Q-factor of the resonator. These characteristics of the resonance peak are controlled, in accordance with the present invention, by modifying the physical parameters of the resonator structure (e.g., dimensions, spacing between waveguides, ring diameter, materials and associated refractive indices, etc.) until the desired peak attributes are achieved, regardless of the Q-factor associated with these optimum attributes.

Abstract: To date, the probes of scanning near-field optical microscopes were aimed at creating electromagnetic field characteristics that are maximally localized near a nano-sized point (miniature apertures and tips, fluorescent nano-particles and molecules, dielectric and metal corners). Alternatively, the probe field, which is distributed within a larger area, can ensure the super-resolution as well. For this purpose, the field spectrum should be enriched with high spatial frequencies corresponding to small sample dimensions. As examples of such near-field probes, we propose and theoretically study the models of optical fibers with end-faces containing sharp linear edges and randomly distributed nanoparticles. These probes are more robust than the conventional probes and their fabrication is not concerned with nanoscale precision. The probes enable waveguiding of light to and from the sample with marginal losses distributing and utilizing the incident light more completely.

Abstract: The specification describes optical devices and related methods wherein an input mode is converted by multiple LPG mode transformers to produce an output with multiple predetermined modes.

Abstract: The specification describes optical devices and related methods wherein the input has multiple modes, and at least one of the multiple modes are respectively converted by one or more multiple mode transformers to produce an output with predetermined modes that are different from the input. In one embodiment the output mode is a single mode. In another embodiment the power ratios of the input modes are controllably changed. In another embodiment one or more output mode is different from the input mode.

Abstract: An electromagnetic device, including: a microfiber or other optical waveguide configured to guide an electromagnetic field output by an electromagnetic field source, the microfiber or other optical waveguide having a diameter that is less than or on an order of a wavelength of the electromagnetic field output by the electromagnetic field source; and a first optical material in contact with the microfiber or other optical waveguide, wherein at least a contact region of the microfiber or other optical waveguide and the first optical material is immersed in a liquid or cured dielectric that has an index of refraction less than the index of refraction of the microfiber or other optical waveguide.

Abstract: An optical resonator is configured for optimized performance as a sensor by maximizing the slope and/or sharpness of the resonance peak, instead of maximizing the Q-factor of the resonator. These characteristics of the resonance peak are controlled, in accordance with the present invention, by modifying the physical parameters of the resonator structure (e.g., dimensions, spacing between waveguides, ring diameter, materials and associated refractive indices, etc.) until the desired peak attributes are achieved, regardless of the Q-factor associated with these optimum attributes.

Abstract: An optical fiber coil of sub-micron diameter is shown to exhibit self-coupling between adjacent turns so as to form a three-dimensional optical resonator of relatively low loss and high Q. As long as the pitch of the coil and propagating wavelength remain on the same order (or less than) the fiber diameter, resonance may occur. Resonances can be induced by allowing adjacent turns of the coil to touch each other. Optical devices such as resonators and interferometers may then be formed from such “microcoils” that exhibit superior characteristics to conventional planar devices. A method of forming such a microfiber using indirect laser heating is also disclosed.

Abstract: An apparatus and method for performing surface microscopy of an optical device uses an optical fiber taper including a microsphere endpoint as a near field probe. A transmission fiber is disposed adjacent to the microsphere so as to evanescently couple an optical test signal into the microsphere. A series of extremely narrow whispering gallery mode (WGM) resonances are created within the microsphere, with an associated electromagnetic field radiating outward therefrom. The microsphere probe may then be moved over the surface of an optical device being analyzed (or the device translated underneath the microsphere), where any abnormalities in the surface (such as defects, scratches and the like) will perturb the electromagnetic field pattern and be reflected in changes in the measured output power from the microsphere.

Abstract: A microstructured optical component is formed from an optical preform fabricated to include one ore more internal regions of differing refractive index. The preform is drawn into a fiber and sliced into relatively long individual fiber segments, each segment thus forming a microstructured optical component. An optical signal may then be coupled through a sidewall of the component in a direction parallel to the endfaces of the segment. A more complex structure can be formed by grouping together a plurality of fiber segments and performing an additional drawing and slicing process.

Abstract: A microstructured optical component is formed from an optical preform fabricated to include one ore more internal regions of differing refractive index. The preform is drawn into a fiber and sliced into relatively long individual fiber segments, each segment thus forming a microstructured optical component. An optical signal may then be coupled through a sidewall of the component in a direction parallel to the endfaces of the segment. A more complex structure can be formed by grouping together a plurality of fiber segments and performing an additional drawing and slicing process.