Abstract: Optical interferometers with variable dispersion are shown. These interferometers are useful as optical interleavers and through the control of their design, are made to have negative and near-zero dispersion. The N-type interleaver has a negative dispersion slope near the center of the pass band. The Z-type interleaver has a dispersion that is close to zero within the pass band. These interleavers can be arranged in various systems to produce low dispersion optical networks. The non-linear phase etalons in the N- and Z-type interleavers taught herein contribute to the device dispersion. The N-Type interleaver includes a linear cavity length that is 1.5 times that of a non-linear cavity. The Z-type interleaver includes two non-linear cavities that are out of phase with each other such that the net dispersion is close to zero.

Abstract: A tunable filter includes a polarizing beam splitter and a half-wave plate that produce two equally polarized beams from an arbitrarily polarized input light. The polarized beams are directed toward a tunable component that consists of an optical substrate coated with a filter and a reflective element on its back and front surface, respectively. The pass and stop beams emerging from the tunable component are retro-reflected by roof structures and passed again through the filter. As a result of this combination of components, the filter's performance is not dependent on polarization and the filter's output channels are not shifted or deviated by tuning.

Abstract: A magnetic recording system containing magnetic recording media with separate data and servo magnetic layers is disclosed. A servo magnetic layer resides usually below the data layer and has higher coercivity than that of the data layer. Interference between the data and servo signals is minimized by recording the servo patterns perpendicular or transverse direction with respect to the orientation of data bits. In addition, servo patterns are selected so that no interference with the data is generated by the servo pattern when the reader is in the middle of data tracks. Tracking error signals are approximately linear with track misregistration around the middle of data tracks. Finally, interference between the data and servo signals is further reduced by electronic processing. Continuous servo signals permit increased track densities with a single actuator and very high track densities with dual microactuator-actuator system.

Abstract: Beam splitter designs for interferometers provide a phase difference between the two resulting interference beams that are independent of the polarization status of the incident beam. The polarization independent phase coating is achieved by making the internal beam splitting coating of an unpolarized beam splitter to be symmetrical. A symmetrical coating will produce the phase matching condition, &PSgr;SR−&PSgr;SR′=&PSgr;PR−&PSgr;PR′=0.

Abstract: A parallel glass plate mounted on a rotating fixture is used to precisely control the optical path length of a light beam. The glass plate refracts the incident optical signal to increase the length of its optical path as a function of the angle of incidence. The device can easily achieve a precision in the order of nanometers and is particularly suitable to fine tune the cavity length of a resonator and the optical path difference of an interferometer. Accordingly, the preferred application of the invention is in an interferometric interleaver. The glass plate can also be coated with a partially reflective coating to attenuate the optical signal passing therethrough. By judiciously selecting the refractive index, the thermal coefficient of refraction, and the coefficient of thermal expansion of the glass, thermal effects may be virtually eliminated.

Abstract: A wide range tunable filter is provided. A randomly polarized incoming beam is converted into two orthogonally polarized beams. A ½ wave plate and filter block turns these two beams into four beams. Two of the four beams have a single range of wavelengths and two beams have the remaining wavelengths. Each pair of beams is orthogonally polarized. A ½ wave plate and birefringent crystal positioned after the filter block combine the two beams having the single range of wavelengths and combines the two beams having the remaining wavelengths. The invention includes a thermal compensator to correct the angle of the filter with respect to the incident light.

Abstract: This invention is an optical communication interleave device using a variety of optical interferometer configurations where one of the beams carries a linear phase and the other beam carries a non-linear phase such that the frequency dependence of the phase difference between these two beams has a step-ike function. The present invention uses a variety of non-linear phase generators to generate this step like phase difference.

Abstract: An opto-electronic device is provided wherein an optical assembly having a first coefficient of thermal expansion is connected to a substrate having a second, different coefficient of thermal expansion. A plurality of stakes are either separately inserted or integrally formed-in the optical assembly and extend through and are adhesively bonded to passageways formed in the substrate. The stakes reduce or prevent differential thermal expansion that would otherwise occur as the device heats up during operation. The substrate may be thermally connected to a metallic housing for the device to increase transfer of unwanted heat into the ambient atmosphere.

Abstract: Apparatus for detecting defects in a substrate comprises a laser for providing a laser beam, and a bi-cell photodiode comprising two cells. Circuitry coupled to the bi-cell photodiode provides a signal equal to (L−R)/(L+R), where L and R equal the signal strengths of the signals provided by the left and right photodiode cells, respectively. The photodiode is biased so that it exhibits reduced capacitance, and can provide increased output signal bandwidth.

Abstract: A cost-effective wavelength division multiplexer and demultiplexer for use in optical communication consists of three modules, including a fiber array, a lens array and a filter array/reflector. Each array is made in wafer level with very precise position control and is bonded to an adjacent wafer by conventional wafer bonding techniques. In addition to eliminating the need for active alignment in the manufacturing process of a wavelength division multiplexer (WDM) transceiver, the invention reduces the footprint of such a device to the order of a few millimeters and the process is suitable for low-cost, large quantity manufacturing. The fiber array is connected to the light sources, which optimally are fiber pig-tailed semiconductor lasers to enable repeatable and accurate placement in reference to the lens array.

Abstract: This invention is an optical communication interleave device using a variety of optical interferometer configurations where one of the beams carries a linear phase and the other beam carries a non-linear phase such that the frequency dependence of the phase difference between these two beams has a step-like function. The present invention uses a variety of non-linear phase generators to generate this step like phase difference.

Abstract: A wide range tunable filter is provided. A randomly polarized incoming beam is converted into two orthogonally polarized beams. A ½ wave plate and filter block turns these two beams into four beams. Two of the four beams have a single range of wavelengths and two beams have the remaining wavelengths. Each pair of beams is orthogonally polarized. A ½ wave plate and birefringent crystal positioned after the filter block combine the two beams having the single range of wavelengths and combines the two beams having the remaining wavelengths. The invention includes a thermal compensator to correct the angle of the filter with respect to the incident light.

Abstract: A variable optical attenuator comprises a collimating element for receiving a light beam originating from an input optical transmission medium, a focusing element opposing the collimating element and operative to substantially focus the light beam upon an output optical transmission medium, and a rotatable optical member (ROM) disposed in between the collimating element and the focusing element and capable of rotating to selectively attenuate the light beam. Attenuation of the beam is accomplished by laterally shifting the beam in the collimating space and producing a cone angle mismatch into an output fiber optic.

Abstract: An edge detection system for detecting pre-formatted marks on a disk surface using reflected beams of optical signals. The detector include at least two separate sensing areas to analyze the energy distribution of the reflected beam to generate an edge detecting signal.

Abstract: A near-field optical system having a mechanism to determine a spacing between an optical surface and a reflective surface that are spaced by less one wavelength by using coupled radiation energy that has an evanescently-coupled portion.

Abstract: The invention is a tunable light source. Techniques for multiplexing various wavelengths into one fiber are provided. A thin film deposition optical monitoring system is provided that utilizes a multiplexer according to the present invention. Light from a multiplexed light source is passed through a fiber optic and emerges from the fiber tip. The light beam is collimated and passes through the substrate where a lens then focuses the transmitted light into a photo-detector. After signal processing, information is sent to the deposition flux source controller to control the deposition rate, coating material and whether deposition should be terminated. An advantage of the present invention over tunable lasers is realized in the low cost of the present invention.

Abstract: An optical disk drive having a thermal control mechanism on the optical head to control the spacing between the optical head and the surface of the storage medium.

Abstract: An opto-electronic device is provided wherein an optical assembly having a first coefficient of thermal expansion is connected to a substrate having a second, different coefficient of thermal expansion. A plurality of stakes are either separately inserted or integrally formed in the optical assembly and extend through and are adhesively bonded to passageways formed in the substrate. The stakes reduce or prevent differential thermal expansion that would otherwise occur as the device heats up during operation. The substrate may be thermally connected to a metallic housing for the device to increase transfer of unwanted heat into the ambient atmosphere.