Abstract: A method and a system for active alignment of a light source assembly along three dimensions in an optical bench plane are provided. The light source assembly, preferably a laser diode on its sub-mount, is actively aligned in three dimensions, longitudinal, transection and vertical along the optical bench. The light source assembly is attached on edge of the optical bench, via adhesion processes, such as solder welding. Optical components such as collimator lens, isolator, etc are first passively aligned on the optical bench using alignment marks and epoxy slots provided on the surface of the optical bench. Then, laser diode, mounted on a laser diode sub-mount, is aligned in X and Z direction. Thereafter, the light source assembly is pushed towards the edge of the optical bench and attached with the edge via a solder joint. Also, a compensator can be actively aligned until the optimum light intensity achieved.

Abstract: An optical isolator includes: an input-side lens converting an operating light incident in a forward direction via an optical fiber input end into parallel light beams; an input-side polarizer disposed on a right hand of the input-side lens; a Faraday rotator rotating a polarization plane of the operating light having been converted into the parallel light beams; an output-side polarizer disposed on an output side of the Faraday rotator; an output-side lens transmitting the operating light having passed through the output-side polarizer; an optical filter blocking light leakage and transmitting the operating light; an optical fiber output end that the operating light exits; and a housing accommodating the input-side lens, the input-side polarizer, the Faraday rotator, the output-side polarizer, the output-side lens, the optical filter and the optical fiber output end therein to enclose them.

Abstract: Various exemplary embodiments relate to an optical isolator in an integrated optical circuit including: a first optical modulator configured to provide a first periodic phase modulation on an input optical signal; a second optical modulator configured to provide a second periodic phase modulation on the modulated optical signal; and an optical waveguide having a length L connecting the first optical modulator to the second optical modulator; wherein the phase difference between the first and second periodic phase modulation is ?/2, and wherein the length L of the optical waveguide causes a phase delay of ?/2 on an optical signal traversing the optical waveguide.

Abstract: An optical isolator including a Faraday rotator that has a high Faraday effect and a high transmission factor in a wavelength used is provided. An optical isolator comprises at least: a Faraday rotator; a polarizer arranged on a light incidence side of the Faraday rotator; and an analyzer arranged on a light exit side of the Faraday rotator, wherein the Faraday rotator consists of an oxide that contains an ytterbium oxide (Yb2O3) with a mass ratio of 30% or more.

Abstract: In an in-line optical isolator, a first polarization separation element 91, a Faraday rotator 6 made of a BIG film, and a second polarization separation element 92 are placed in that order. The isolator further includes a first optical fiber collimator 1a being placed at the forward-beam incident side of the first polarization separation element 91 and including a collimating lens 101 and a first optical fiber 31, and a second optical fiber collimator 2a being placed at the forward-beam exit side of the second polarization separation element 92 and including a collimating lens 102 and a second optical fiber 32 connected to a fiber amplifier. Also, an edge filter 100, which transmits light emitted from the first optical fiber 31 and having a wavelength equal to an oscillation wavelength and which reflects light emitted from the first optical fiber 31 and having wavelengths shorter than this wavelength, is placed between the second optical fiber collimator 2a and the second polarization separation element 92.

Abstract: A double stage isolator is formed of face-to-face slabs or sheets of materials that will suitably split, combine, non-reciprocally rotate to ensure isolation in a reverse direction from output ports to respective input ports of any light launched into the input ports. A right angled Porro-prism is disposed at an end of the affixed together slabs having planar faces to direct light launched in a folded fashion to the output ports. A half waveplate is used in addition to beam splitter combiners and non-reciprocal rotators means that rotate the light by 90 degrees so as to pass a single beam in a forward propagating direction and to interchange the polarization of two sub-beams that pass through from an output port to an input port in a reverse direction.

Abstract: A heat-dissipating structure for an optical isolator is capable of suppressing an increase in temperature caused by light absorption in a magnetic garnet crystalline film by radiation fins extending from the inside of an external heat conducting cover. The heat-dissipating structure for the optical isolator is formed by housing a magnetic garnet crystalline film (12), first and second heat conductive plates (6, 7, 8 and 9) and magnet 18 in the external heat conducting cover, placing the radiation fins (10 and 11) on the second heat conductive plate, attaching the first heat conductive plates (6 and 7) onto either side of the magnetic garnet crystalline film, arranging the second heat conductive plates (8 and 9) on the outer surface of the first heat conductive plates, and passing the radiation fins through guide openings (2a and 2b) in the isolator holder 2 to the outside of the external heat conductive cover from the extracting opening (3c) to be brought into contact with the outer grooves (4d and 5d).

Abstract: A laser module including a first housing which encloses a semiconductor laser device, a support, a fiber sleeve for holding an optical fiber, a lens, and an isolator. The isolator and the fiber sleeve are jointly arranged within a second housing which is an integral holder holding both the isolator and the fiber sleeve.

Abstract: An optical isolator is constructed such that an optical isolator element in which at least one flat Faraday rotator and at least two flat polarizers are bonded to each other into an integral unit by van der Waals forces or hydrogen-bonding forces acting between bonding surfaces of the Faraday rotator and the polarizers is accommodated in a tubular magnetic element.

Abstract: A passively aligned optical isolator includes laminated layers of material including two polarizing glass layers sandwiching a Faraday rotator layer. Each polarizing glass layer comprises a glass matrix containing elongated metal particles exhibiting a change in polarization axis of less than about 0.0375°/m over a distance of at least 8 mm, as measured across a major surface of the layer. The optical isolator has a contrast ratio greater than 40 dB.

Abstract: An isolator is disclosed that features a single birefringent correction element. The correction element is configured to eliminate differential group delay and walk-off simultaneously.

Abstract: A first separating/combining birefringent element 10, first and second optical-path controlling birefringent elements 11, 12, and a second separating/combining birefringent element 13 are spaced apart. Between the first separating/combining birefringent element and the first optical-path controlling birefringent element, a first polarization rotating means 14 is arranged for changing a polarization direction from an orthogonal relationship to a parallel relationship, or from a parallel relationship to an orthogonal relationship. Also, between the second optical-path controlling birefringent element and the second separating/combining birefringent element, a second polarization rotating means 17 is arranged.

Abstract: An optical semiconductor device comprises a semiconductor laser (11) including a lower clad layer, an active layer (4), and an upper layer formed in this order, an electroabsorptive modulator (12) including the lower clad, a light absorption layer (6), and the upper clad layer formed in this order, and a separation region (13) provided between the semiconductor laser and the electroabsorptive modulator. The upper clad layer extends from the semiconductor laser through the separation region to the electroabsorptive modulator and up to the side of the separation region.

Abstract: An optical isolator includes a first stage configured to refract a light ray applied in a forward direction into a first ray and a second ray. A second stage rotated 90° with respect to the first is configured to refract said first and second rays in a substantially parallel manner. The isolator is configured such that the first ray comprises an e-ray with respect to the first stage and an o-ray with respect to the second stage, and the second ray comprises an o-ray with respect to the first stage and an e-ray with respect to the second stage, thereby substantially reducing the effects of polarization mode dispersion.

Abstract: An optical fiber amplifier module is disclosed which comprises a signal path located between a signal input and a signal output. A WDM coupler and an amplifying gain medium are disposed along the signal path. A pump laser is disposed out of the signal path in a manner that allows a pump signal from the pump laser to reflect off the WDM coupler and enter the signal path. An embodiment utilizing a second WDM coupler and a second pump laser is also disclosed.

Abstract: Optical isolators and methods of manufacturing optical isolators are disclosed. The optical isolators are manufactured by directly bonding the parts of the isolators without the use of adhesive or mechanical devices to hold the individual parts together.

Abstract: Methods and apparatus for optimizing feedback suppression of optical isolators when used with variable wavelength light sources. The methods comprise positioning an optical isolator in a light beam, and adjusting feedback suppression by the optical isolator according to wavelength of the light beam. Adjusting the feedback suppression may comprise adjusting temperature of the optical isolator or a non-reciprocal rotator associated with the isolator.

Abstract: An optical system provides reflection-type isolation, and may include variable optical attenuation and/or a tap monitor. The optical system may include an optical isolator with a beam splitter such as a walk-off plate, a focusing element such as a GRIN lens, a combiner comprising two birefringent wedges and a non-reciprocal rotating device such as a Faraday rotator, a compensation device, and a reflector. The Faraday rotator may be variable to provide variable attenuation. The reflector may be a partial reflector to provide a tap monitor. The optical system is configured so that light transmitted into the optical isolator through the input fiber may be transmitted out of the optical isolator through the output fiber, but light transmitted into the optical isolator through the output fiber is generally not transmitted out of the optical isolator through the input fiber.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: An optical device and method of manufacture are disclosed. The optical isolator includes a substrate comprising a magnetic material such as a Garnet. Respective sets of essentially parallel conductors are selectively formed on both major surfaces of the substrate. The set on one surface is at a selected angle with respect to the set on the other surface.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: The invention provides a semiconductor laser module and an optical transmission system, with which noise caused by light reflected back from a transmission path can be suppressed. The semiconductor laser module, includes a package having a window, a semiconductor laser chip outputting light, a lens that is optically designed such that it couples the light that is output by the semiconductor laser chip into an optical transmission path, an optical isolator that is disposed between the lens and the window, a temperature control mechanism for keeping temperature of these components constant, and a tubular ferrule that is holds and covers the optical transmission path. The semiconductor laser chip, the lens, the optical isolator, and the temperature control mechanism are arranged inside the package. A polarizer is arranged at an end face of the ferrule on the side of the package, such that the polarizer matches a polarization plane of the light that is emitted through the window of the package.

Abstract: Optical isolators and methods of manufacturing optical isolators are disclosed. The optical isolators are manufactured by directly bonding the parts of the isolators without the use of adhesive or mechanical devices to hold the individual parts together.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device according to the present invention includes a spatial walkoff plate (SWP) coupled on opposite ends to first and second polarization orientation elements. First and second polarization beam splitter (PBS) elements are coupled to the first and second polarization orientation elements, respectively. The PBS elements are formed using thin film coating techniques and each includes an array of port coupling regions for coupling to an array of input/output fiber port assemblies. The SWP may be formed using thin film coating techniques or cut from a birefringent single crystal. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, each also includes a wave plate formed using thin film coating techniques.

Abstract: In another aspect, the invention provides a closed loop optical circulator including a first crystal for splitting an input light signal into two components, a second crystal for deflecting the two components received from the first crystal in a direction if the two components have a first polarization, a third crystal for deflecting the two components received from the second crystal in an opposite direction if the two components have the first polarization, and a fourth crystal for joining the two components received from the third crystal.

Abstract: The present invention provides improved optical switches in which no mechanical movement is required to direct optical pathways between plural fiber ports. Advantageously, the inventive switches incorporate two-stage polarization rotation to improve isolation depth, as well as temperature and wavelength independence. The inventive switches also incorporate light bending devices to allow two fibers to be coupled to the light beams using a single lens achieving small beam separation for compactness. In the inventive switch, an optical signal is spatially split into two polarized beams by a birefringent element, which passes through a polarization rotation device that comprises waveplates, walk-off elements, and electrically controllable polarization rotators, and recombine into an output fiber, achieving polarization independent operation.

Abstract: State of polarization detectors and polarization control systems are disclosed. For example, the invention features an integrated optical assembly including: (i) a series of polarization-sensitive interfaces defining an optical beam path for an input optical beam to pass through the assembly, wherein each polarization-sensitive interface derives a sample beam from the input beam; and (ii) one or more retardation layers each positioned between a different pair of the polarization-sensitive interfaces, wherein the retardation layers are integrally coupled with the polarization-sensitive interfaces, and wherein the retardation layers and polarization-sensitive interfaces cause each sample beam to have an intensity that provides different information about the state of polarization of the input beam.

Abstract: A light emitting apparatus has a light generating portion, an output, and an optical isolator. The light generating portion includes a semiconductor optical amplifier and a grating fiber. The semiconductor optical amplifier has a light emitting surface and a light reflecting surface, and the grating fiber has a first end optically coupled to the light emitting surface, and a grating provided in its core part. The output is designed to provide light generated in the light generating portion. An optical isolator is placed between the light generating portion and the output. In the light emitting apparatus, the isolation of the optical isolator is specified to be not less than −52.4−8.7×log(BER) in dB with respect to a bit error rate BER to be achieved at the transmission rate of 2.5 Gbps in the 1.55-&mgr;m band.

Abstract: Polarization compensators and devices and systems incorporating them including polarization rotator means that employ novel polarization compensation means. The novel polarization compensator means employs the use of a variable retarder means with retardation dependent on environmental, system or operating requirements coupled with a second retarder means of substantially 90 degrees of retardation at the center specification conditions of operation. The polarization compensator may be part of either a reciprocal or a non-reciprocal device also having Faraday rotator means with specific dependence on temperature and wavelength. To improve performance significantly, temperature and/or wavelength dependence of the variable retarder of the invention is adjusted to be between about 1 and 3 times and preferably between about 1.5 and 2.5 times) the temperature and/or wavelength dependence of the Faraday rotator.

Abstract: Methods and apparatus for optimizing feedback suppression of optical isolators when used with variable wavelength light sources. The methods comprise positioning an optical isolator in a light beam, and adjusting feedback suppression by the optical isolator according to wavelength of the light beam. Adjusting the feedback suppression may comprise adjusting temperature of the optical isolator or a non-reciprocal rotator associated with the isolator.

Abstract: A new low-cost free-space optical isolator is disclosed in this invention. The new free-space optical isolator includes an input polarizer, a Faraday rotator, an output polarizer, and a magnetic tube. By employing the recently developed subwavelength optical elements (SOEs) technology, the input polarizer is directly manufactured on the left surface of the Faraday rotator and the output polarizer is directly manufactured on the right surface of the Faraday rotator. Relative to the polarization axis of the input polarizer, the polarization axis of the output polarizer is 45 degrees clockwise from left to right.

Abstract: An optical isolator includes a first magnetic polar source having a first magnet axis, a second magnetic polar source having a second magnet axis parallel to the first magnet axis, and an optical element between the first and second magnetic polar sources, and having a length along the first magnet axis that is less than a length of the first magnetic polar source along the first magnet axis. The optical element has a central axis that is tilted with respect to the second magnet axis.

Abstract: Optical isolators and methods of manufacturing optical isolators are disclosed. The optical isolators are manufactured by directly bonding the parts of the isolators without the use of adhesive or mechanical devices to hold the individual parts together.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: An optical isolator comprising at least a first birefringent polarization element, a 45° faraday rotator, a first ½ waveplate, a second ½ waveplate, and a second birefringent polarization element arranged in this order, wherein the first and second ½ waveplates reciprocally rotate. polarization planes of signal light at 45° in total while canceling out wavelength dispersion of retardation, and there is provided a single-stage type optical isolator of low cost having small coupling loss in the forward direction and having good isolation characteristics in the backward direction.

Abstract: There are provided a manufacturing method of an optical device excellent in expediency, and a technique for stably manufacturing a high performance optical device. After a single crystal film which constitutes a Faraday rotator and can exhibit a substantially rectangular magnetic hysteresis, is obtained, the single crystal film is magnetized in a state where this single crystal film is incorporated in an optical device such as an optical isolator. By performing a magnetizing step after the Faraday rotator is incorporated in the optical device, it becomes unnecessary to discriminate between the front and back surfaces of the single crystal film, and the characteristics of the optical device are also improved.

Abstract: An optical element comprises a Faraday rotator and first, second, third, and fourth birefringent regions. The first and second regions and a fifth region are joined to one plane of the rotator. The third and fourth regions and a sixth region are joined to the opposite place of the rotator. Light that has passed through the first region passes through the third region. Light that has passed through the second region passes through the fourth region. The optical axes of the first and second regions intersect orthogonally. The optical axes of the third and fourth regions intersect orthogonally. The principal planes of the first and second regions have the same ground surfaces. The principal planes of the third and fourth regions have the same ground surfaces. The first through fourth regions are of the same material. At most 10% of the light beam travels through the fifth and sixth regions.

Abstract: A polarization-independent optical isolator includes a first birefringent wedge plate having an inclined plane directed to a light incoming side; a second birefringent wedge plate having an inclined plane directed to a light outgoing side, the wedge equal thickness line of the inclined plane of the second birefringent wedge plate being in parallel to the wedge equal thickness line of the inclined plane of the first birefringent wedge plate; and a Faraday rotator element disposed between the first and second birefringent wedge plates. A non-inclined plane of the first birefringent wedge plate is adhesively bonded to a light incoming plane of the Faraday rotator element, and a light outgoing plane of the Faraday rotator element is adhesively bonded to a non-inclined plane of the second birefringent wedge plate. The first and second birefringent wedge plates and the Faraday rotator element thus adhesively bonded to each other are disposed in a cylindrical magnet.

Abstract: Bi-directional wavelength interleaving optical isolators provide the ability to pass a first set of optical signals (e.g., ITU even channels) from a first port to a second port, while preventing a second set of optical signals from passing thereto. The bi-directional wavelength interleaving optical isolators also pass the second set of optical signals (e.g., ITU odd channels) from the second port to the first port, while preventing the first set of optical signals from passing thereto. Thus, the bi-directional wavelength interleaving optical isolator can provide bi-directional communications by passing a first set of signals in a first direction and a second set of signals in a second direction.

Abstract: An optical isolator includes a first pigtail assembly, a first collimating lens aligned with the first pigtail assembly, an optical rotator assembly, an adjustable assembly aligned with the rotator assembly, and a second pigtail assembly having a ferrule and a second optical fiber with an end attached within the ferrule. The rotator assembly includes a first birefringent wedge, an optical rotator and a magnet. The adjustable assembly includes a second birefringent wedge, a second collimating lens, and a holder holding at least a portion of the second birefringent wedge and at least a portion of the second collimating lens therein. The magnet of the rotator assembly encloses the first birefringent wedge and the rotator. The rotator is positioned between the first and second birefringent wedges. The adjustable assembly is adjustable relative to the rotator assembly. This achieves precise positional relationships among the rotator and the first and second birefringent wedges.

Abstract: A circulator array is constructed in a planar substrate by forming a plurality of waveguide pair structures, each waveguide pair structure having first and second sections respectively coupled by first and second polarization multiplexers. A nonreciprocal polarization rotation element is positioned in the optical paths of the waveguide pair structures and is configured to rotate the polarization of light passing from the second sections of the waveguides to the first sections while leaving unchanged the polarization of light passing from the first sections to the second sections, such that optical signals received at one port of the circulator structure are routed along a predetermined path to another port of the circulator structure.

Abstract: An optical fiber amplifier module is disclosed which comprises a signal path locatee between a signal input and a signal output. A WDM coupler and an amplifying gain medium are disposed along the signal path. A pump laser is disposed out of the signal path in a manner that allows a pump signal from the pump laser to reflect off the WDM coupler and enter the signal path. An embodiment utilizing a second WDM coupler and a second pump laser is also disclosed.

Abstract: A conventional interleaver, based on a stack of waveplates, relies on the orientation and the birefringence of the waveplates to differentiate the polarizations of one set of channels from another, so that the one set of channels can be separated from the other. The present invention relates to a virtual waveplate that is used to replace a birefringent waveplate. A virtual waveplate imposes a phase delay between the extraordinary ray and the ordinary ray by separating one from the other and differentiating the actual path lengths taken thereby, before recombining them. An interleaver constructed with the virtual waveplates of the present invention can be substantially a-thermal and potentially chromatic dispersion free.

Abstract: Polarized glass articles and method of manufacturing polarizing glass articles are disclosed. Optical isolators using the polarizing glass articles have reduced coupling and surface losses when compared with conventional optical isolators.

Abstract: A reflective doped fiber amplifier array utilizes an integrated circulator array to effect routing of optical signals. The integrated circulator array has a plurality of waveguide pairs coupled by polarization multiplexers formed in a planar substrate, and a nonreciprocal polarization rotation element positioned between sections of the waveguide pairs. Pump light is coupled into and out of the doped fibers by wavelength-selective reflectors.

Abstract: The invention is an instrument for sensing the state of polarization (SOP), and for transforming the SOP of a beam of light from an incident continuously-varying arbitrary SOP to a desired exit SOP, using a polarization compensator under feedback control. A polarization sensor uses two or three samples of a beam to sense the Poincare sphere latitude and longitude error in SOP. A polarization controller adjusts the SOP of light, which is then sensed by the polarization sensor, which develops signals to drive the polarization compensator using feedback methods. Unlike prior-art systems, the feedback seeks a mid-point rather than an extremum in the sensed signals, so there is no sign ambiguity in the feedback control. Further, the sensor signals indicate orthogonal displacements in SOP that correspond to specific elements in the polarization controller, so there is no ambiguity as to which element needs adjustment in order to correct a given error in SOP.

Abstract: If an optical path length of an optical system is reduced and a length of a laser light on an irradiation surface is increased, there occurs curvature of field which is a phenomenon that a convergent position deviates depending on an incident angle or incident position of a laser light with respect to a lens. To avoid this phenomenon, an optical element having a negative power such as a concave lens or a concave cylindrical lens is inserted to regulate the optical path length of the laser light and a convergent position is made coincident with a irradiation surface to form an image on the irradiation surface.

Abstract: A double-stage (multi-stage) optical isolator is composed of two pairs of birefringent wedges (polarizers) with a Faraday rotator sandwiched by a pair of the wedges. The wedge-shaped polarizers, each defining a wedge angle, are disposed such that the wedges of the third and fourth polarizer (second stage) are arranged generally opposite relative to the wedges of the first and second polarizer (first stage) respectively, the wedge angles and the angles of incidence in the forward direction selected such as to minimize offset between the line of propagation of an optical beam passing through the isolator in the forward direction. The isolator has a PMD compensation element disposed between the first and the second stage to minimize polarization mode dispersion of light beams propagating through the isolator. The isolator has a very low PDL, virtually no PMD, high isolation and virtually no displacement (offset) between the input beam and out beam line of propagation.

Abstract: A planar-type optical isolator includes a substrate, a first mode splitter, a second mode splitter and a phase shift region formed on the substrate between the first mode splitter and the second mode splitter. The first mode splitter is formed on the substrate and receives an incident optical signal through an input port and splits the incident optical signal into a first incident mode and a second incident mode. The second optical splitter is formed on the substrate and combines a first rotated incident mode and a second rotated incident mode to reform the incident optical signal at an output port. The second mode splitter receives a reflected optical signal on the output port and splits the reflected optical signal into a first reflected mode and a second reflected mode. The phase shift region is formed on the substrate between the first mode splitter and the second mode splitter and includes a nonreciprocal phase shift section and reciprocal phase shift section.

Abstract: A fiber optic isolator device is used by fiber optic systems operating at more than one wavelength. The device may be inserted anywhere within the fiber network. The fiber optic device permits the separation of the wavelengths so that an optical isolator module can isolate a first wavelength without significantly affecting the second wavelength. This device is useful isolating a communications signal at 1.55 &mgr;m while avoiding significant losses for an optical time domain reflectometry signal, for example at 1.3 &mgr;m.