Abstract: Lasing at the edge of the reflection band or at a defect state within the reflection band of a thin one-dimensional feedback structure is used to create a large-area, thin-film laser source with transverse dimensions that can be much greater than the film thickness. Angular confinement of radiation propagating perpendicular to the layers leads to a spreading of the beam inside the medium which is much greater than the diffraction divergence. This enhances the spatial extent of correlation at the output surface of the thin film. When a pump source induces gain at the lasing threshold in a wide region, a spatially coherent monochromatic light beam is emitted perpendicular to the film surface from the entire gain region. Alternate embodiments of the present invention include a passive spatial filter and an active amplifier.

Abstract: A thin chiral film display is provided in several embodiments. In one inventive embodiment, red, green and blue chiral film lasers are placed in front of corresponding red, green and blue LCD panels connected to a video signal source. The resulting red, green and blue signal components are combined and output through a projection lens onto a screen or other surface. In another inventive embodiment, red, green and blue chiral film lasers are pixellated and each connected to a video signal source. The pixels are under the control of the video signal source and serve to replace the LCDs from the previously described embodiment. The resulting red, green and blue signal components are combined and output through a projection lens onto a screen or other surface. In another inventive embodiment, red, green and blue chiral film lasers are pixellated and each connected to a video signal source.

Abstract: A thin chiral film display is provided in several embodiments. In one inventive embodiment, an array of chiral lasers is utilized in a passive or active matrix display configuration. In another embodiment of the present invention, at least one chiral laser is used as a highly efficient low cost backlight for a conventional passive or active matrix display or microdisplay.

Abstract: A apodized chiral fiber grating consists of a chiral fiber with a variable effective grating strength along different regions of its length, such that the effective grating strength gradually increases from one end of the chiral fiber until a peak effective grating strength is reached and then gradually decreases at the same rate towards the other end of the fiber. Optionally, the effective grating strength remains stable for a portion of the fiber before decreasing. Other forms of grating strength variations in different regions of the chiral fiber are also contemplated. The effective grating strength variation produces an apodized chiral fiber that possesses desirable characteristics that greatly reduce or eliminate the sidelobes in the fiber's spectral response.

Abstract: A long period chiral fiber grating (“LPCFG”) that has a number of advantageous properties that can be readily utilized in a number of different applications is provided. The inventive LPCFG is a fiber grating having a pitch that exceeds the wavelength of light propagating therethrough. The LPCFG includes a number of dips in its transmission spectrum, but does not reflect any portion of the signal passing therethrough. The LPCFG is sensitive to changes in the refractive index of its external environment (or in the refractive index of a coating covering the LPCFG cladding). In response to changes in the external refractive index, the transmission dips shift proportionally to changes in the index, thus enabling the use of LPCFG as a fiber sensor element. In addition, the LPCFG is polarization sensitive—one circular polarized wave of one handedness is coupled to the cladding mode stronger than the wave of the other polarization handedness.

Abstract: A chiral structure having an advantageous extended chiral defect that provides an enhanced energy distribution characteristic therein. This is accomplished by configuring a central portion of the chiral structure with a pitch different from the rest of the structure. This may be envisioned as a distributed chiral twist with a predefined angle over a portion of a chiral structure. With the distributed defect, the photonic stop band remains wide, allowing for the substantial increase in the lifetime of the mode in which lasing occurs, while the extent of the high intensity region of the mode is large. The extended chiral defect structure may also be implemented as a thin-film chiral structure, for example using cholesteric liquid crystal or sculptured thin films.

Abstract: A chiral structure having an expanded adjustable reflection band to provide broadband tunability is provided. In the preferred embodiment, the chiral structure is implemented as a chiral fiber structure and comprises two or more sequential chiral fiber elements of different pitches, each having a tunable chiral defect generator. The pitches are selected such that the individual photonic band gaps of the elements are formed into one expanded reflection band such that at least one defect state can be formed and moved within the expanded reflection band by selectively activating and adjusting one or more of the tunable chiral defect generator. The tunable chiral defect generators may generate and control defect state(s) in the structure's spectral response by introducing chiral twists and/or spacing between the chiral elements, with the length of the spacings and angles of chiral twists being proportional to the position of the defect state(s) within the reflection band of the structure.

Abstract: A chirped chiral fiber usable in dispersion compensators and other applications consists of a chiral fiber with a variable period along its length. Advantageously, the inventive chirped chiral fiber is customizable to any specific dispersion compensation application by selectively controlling the pitch along the fiber length. A chromatic dispersion compensator utilizing the inventive chirped chiral fiber and a circulator is also disclosed.

Abstract: A chiral in-fiber tunable polarizer implemented in a chiral fiber structure is provided. The chiral fiber is selected with a predetermined handedness and scatters (by reflecting, coupling into the fiber core or otherwise) the circularly polarized light matching its handedness while transmitting circularly polarized light of opposite handedness. By combining the chiral fiber with another fiber component having a non-cylindrical core, the inventive apparatus produces a linearly polarized wave with a predetermined orientation. The orientation may be adjusted by rotating the fiber component around its central axis. The chiral fiber structure may be configured as a long period chiral fiber grating. Optionally, the chiral fiber structure may be configured with a variable pitch along its length, such as a chirped fiber grating, an apodized fiber grating, or a set of multiple sequential chiral polarizer elements with different pitches.

Abstract: A chiral fiber sensor implemented in a chiral fiber is provided that mimics advantageous optical properties of a cholesteric liquid crystal structure. In a passive sensor embodiment the chiral fiber sensor of the present invention includes a chiral fiber element configured to shift its reflection band in response to a change in a particular external condition (such as temperature, pressure and axial twist). The chiral fiber element is subjected to a broadband emission while monitoring its refection or the transmission spectrum. Changes in the monitored spectrum indicate changes in the particular external condition. In an active sensor embodiment, the chiral fiber element is configured as an optically pumped chiral laser having a lasing wavelength that shifts in response to a change in a particular external condition (such as temperature, pressure and axial twist). The lasing wavelength is monitored and shifts in the wavelength indicate changes in the particular external condition.

Abstract: A chiral fiber laser implemented in a fiber Bragg grating mimicking the advantageous optical properties of a cholesteric liquid crystal structure is provided. The dopant, the pitch, the core cross section and dimensions thereof, of the inventive chiral fiber laser as well as the core and cladding materials used in construction thereof, may be advantageously selected and configured to enable the inventive chiral fiber laser to produce lasing at a desirable wavelength. In another embodiment of the inventive chiral fiber laser, a tunable defect is introduced to provide tunable lasing corresponding to the wavelength at the defect mode. Multiple embodiments using coupled fiber optical pumping as well as direct optical pumping for excitation of the inventive chiral fiber laser are provided.

Abstract: An apparatus and method for fabricating a thin layer periodic structure by successively depositing alternating uniform layers of two or more different dielectric materials on a substrate utilizing centrifugal force in a novel spin coating technique. In an alternate embodiment of the present invention, the novel spin-coating technique is configured for fabricating chiral media by successively depositing layers of one or more anisotropic materials, while rotating the substrate by a predetermined angle between deposition of each layer. In both embodiments of the inventive apparatus, a defect layer may be introduced by depositing a defect material in a desired position in the media.

Abstract: An apparatus and method for fabricating fiber gratings from optical fibers by imposing constant or variable chiral refractive index modulation along an optical fiber. The refractive index modulation may be of single helix symmetry to produce a fiber grating enabling different propagation speed of signals with the same handedness as the structure with respect to signals with opposite handedness as the structure at a wavelength substantially equal to the pitch of the single helix, or of double helix symmetry to produce a chiral fiber Bragg grating. In several embodiments of the present invention the refractive index modulation is imposed by twisting and moving a specially prepared optical fiber through a heater that heats a small region of the fiber to a temperature sufficient to allow the fiber to twist in that region as it moves through the heater.

Abstract: An add-drop filter, utilizing chiral couplers, that enables a new signal to be added at a particular vacuum wavelength &lgr;′k to a fiber optic line carrying n signal channels over a band of wavelengths encompassing &lgr;1 . . . &lgr;k−1, &lgr;k, &lgr;k+1 . . . &lgr;n, while an existing signal, &lgr;k, is simultaneously dropped from the signal group.

Abstract: A fiber Bragg grating comprises a chiral fiber mimicking a cholesteric liquid crystal structure, having a first and a second helical structures disposed along its central longitudinal axis, where the second helical structure is identical in orientation to the first helical structure but is shifted by one half of the structure's pitch forward. In another embodiment of the invention, only a single helical structure is disposed along the fiber to create an optically resonant chiral fiber.

Abstract: Lasing at the edge of the reflection band or at a defect state within the reflection band of a thin one-dimensional periodic structure is used to create a large-area, thin-film laser source with transverse dimensions that can be much greater than the film thickness. Angular confinement of radiation propagating perpendicular to the layers leads to a spreading of the beam inside the medium which is much greater than the diffraction divergence. This enhances the spatial extent of correlation at the output surface of the thin film. When a pump source induces gain at the lasing threshold in a wide region, a spatially coherent monochromatic light beam is emitted perpendicular to the film surface from the entire gain region. Alternate embodiments of the present invention include a passive spatial filter and an active amplifier.

Abstract: In accordance with the apparatus and method of the present invention an optical fiber is heated and twisted to produce a periodic modulation of the dielectric constant along the fiber axis. This structure can be used in any application that utilizes Bragg grating optical fibers. A preform is drawn through a heater and the resulting optical fiber is twisted about its longitudinal axis. The refractive index modulation in the optical fiber arises from birefringence induced by stress in the optical fiber that is twisted after being subjected to an uneven heat distribution during the drawing process. The refractive index is modulated by drawing and twisting the optical fiber from a specially constructed preform which is non-cylindrically symmetrical.

Abstract: An add-drop filter, utilizing chiral elements, that enables a new signal to be added at a particular vacuum wavelength &lgr;′k to a fiber optic line carrying n signal channels over a band of wavelengths encompassing &lgr;1 . . . &lgr;k−1, &lgr;k, &lgr;k+1 . . . &lgr;n, while an existing signal, &lgr;k, is simultaneously dropped from the signal group.

Abstract: An apparatus and method for manufacturing chiral fibers having chiral fiber Bragg gratings properties from UV sensitive optical fibers by using a UV laser beam to impose a chiral modulation of the refractive index at the core of the fiber.

Abstract: Band gap lasers based upon activated periodic one-dimensional structures are disclosed. The periodic structures may be cholesteric liquid crystals, other chiral materials, or materials with alternating dielectric layers with different indices of refraction. The amplifying component may be an organic dye, rare earth or other ion, conjugated polymer, or other luminescent materials. Lasing occurs at a predetermined frequency corresponding to that of modes at the edge of the stop band in these periodic structures or to the frequency of a defect mode introduced into the structure. The lasing threshold may be lowered and the efficiency raised by the following further considerations: Adjacent layers of different period, and correspondingly different stop band, are incorporated into the structure to serve as reflectors on either or both sides of the active medium. The peak emission of the active medium is chosen to be close to the frequency of one of the long-lived photon modes of the system.