Abstract: The invention describes a method of single-transverse-mode generation for waveguide lasers of various kinds having a large cross section of their active core and thus providing a possibility of efficient pump of the active core region. This results in a laser beam with enhanced power and high spatial quality for high efficiency coupling to standard single-mode optical fiber networks. It is found that a multimode waveguide having a central dip of special shape in the refractive index profile of its core is able to guide a higher order mode with sharp central peak of its field carrying the considerable part on the mode energy and whose width is well compatible with the width of the fundamental mode of standard single-mode fibers. The useful properties of this higher order mode can be employed to provide the single-transverse-mode regime of generation in optical fiber lasers, integrated optical micro-lasers and various semiconductor laser sources.

Abstract: An optical spectrum analyzer based on optical processing of the far field interference pattern from two beams irradiated by light transmitting waveguides is described. The spectrum analyzer can operate in UV, VIS, NIR and MIR ranges of spectrum and it can be based on either optical fibers (multimode or single-mode) or integrated optical waveguides. It has many important applications, for example, as a simple, compact and inexpensive spectrum analyzer used with fiber optic chemical and biological sensors.

Abstract: The invention describes two types of multimode optical waveguides having special dip in the refractive index profile of their core providing conditions for propagation of a higher order mode with sharp central peak which field carries considerable part of the mode energy, while the fields of all other modes in the waveguide are mostly concentrated outside of this central peak region. The waveguide of the first type guides the mode only with one central peak while the mode in the waveguide of the second type has also an additional peak at the interface between the waveguide core and cladding providing a possibility to detect any influence on the mode field in its outer region by measuring the signal in the central peak of the mode.

Abstract: A method for efficiently coupling beams from semiconductor lasers into optical fibers is presented which provides optical fibers with a modified end surface for efficient coupling. The method comprises a combination of shaping of the fiber end face and of axially varying the refractive index of the fiber end face material as a function of the distance from fiber end face surface. One preferred embodiment employs an axial gradient-index lens (AGRIN lens) fabricated directly on the fiber end face to improve coupling a laser beam into the fiber. The method can also be used in other applications where optical fibers having spherical or more complicated surfaces of their end faces need to be fabricated.

Abstract: Linearly distributed illumination systems based on flexible optical waveguides or optical fibers are described for both high brightness and low brightness applications. Light illumination at preselected locations is accomplished by transferring light from the light carrying core region to the outer layers of the waveguide/fiber structure. A curled waveguide, typically having a rectangular band-like core cross section and cut at an angle facing the light source, serves to optically couple light with simplicity and high efficiency into the waveguide for high brightness applications. Grooves into sides of the band waveguide, in either the small or large dimension, provide a means for removing light from the core to illuminate preselected regions along the length of the band waveguide. Complex systems comprising a bundle of band waveguides and an optical feedback means for automatic control of illumination brightness are also described.

Abstract: A compound laser system for generating beams of high brightness and high power density by constructive phase coherent combination of the beams generated by a number of individual sources of coherent radiation three subsystems: a diode laser subsystem which is the source of power for the system; a combiner subsystem which combines the output of the diode lasers; and, an optional delivery subsystem which may be needed to deliver the combined output to its desired destination for industrial or medical applications. The combiner subsystem may be implemented in its entirety as an Integrated Optical Combiner, a single component performing all the combiner subsystem's functions. A preferred embodiments of the combine subsystem employs optical fibers having shaped cores to provide efficient matching to the geometry of typical laser diodes.

Abstract: A new family of lasers and optical parametric oscillators is based on efficient frequency conversion or doubling in multimode compound optical waveguides. These waveguides exploit specific useful properties of their higher order modes while providing good compatibility with single-mode optical fibers. A mode engineering approach is applied to construct a compound waveguide structure that supports a higher order mode having a sharp peak in its field. This sharp peak simplifies selection of this mode by efficient coupling of its radiation into a single-mode fiber. The lasers and optical parametric oscillators employ wavelength selective properties of this mode field configuration and its unique ability to support efficient frequency conversion and doubling.

Abstract: A flexible fiber optic delivery system for medical and industrial applications is described that can transmit high laser power densities and optical images. A parabolic-index profile of a graded-index fiber is perturbed so as to prevent strong localization of a laser beam in the fiber's recurring focal regions. This permits transmission of high laser powers without danger of fiber damage. An additional gain in carrying capacity for the system is achieved by using a wavefront perturbation system between the laser source and the graded-index fiber. Optical image transmission is achieved by using a measured perturbation to a parabolic-index profile of the graded-index fiber with a prescribed length and a wavefront reconstruction system in combination with the wavefront perturbation system. The system has an increased laser induced damage threshold and can transmit highly focused optical images.

Abstract: A multichannel connector for transmission of optical signals between a number of input and output channels through a rotating interface is described. The connector comprises an input and an output platforms rotating around their common axis and an optical system connecting input optical signal channels to output optical channels independent on relative rotation of the platforms. The connector conserves both the amplitude and phase of the optical signals transmitted between the input and output channels. The optical system comprises either a combination of lenses and prism rings or single computer generated hologram. It can be used, for example, for connection between input and output bundles of optical fibers through a rotation interface without cross talk of the optical signals. The connector can find important industrial, military and medical applications where the optical signals from a number of channels are to be transmitted through rotating junctions.