Abstract: The invention relates to a method of manufacturing an indiffused optical waveguide (6) in a substrate (1). A metal layer (7) and photoresist (8) are deposited on a substrate (1) in this order. Portions of the photoresist (8) are removed such that a photoresist structure (8) corresponding to the desired waveguide structure is left. The exposed portions of the metal layer (7) are removed by a chemical/physical etching technique whereafter the remaining photoresist (8) is removed and the remaining metal layer (7) is diffused into the substrate (1) by a heat treatment. The usage of a chemical/physical etching method for removing portions of the metal layer (7) results in smaller variations in the width of the waveguide after indiffusion. Such waveguides are particularly advantageous when being used in connection with acousto-optical devices. The optical waveguides according to the invention are also useable with other integrated optics devices.

Abstract: An optical signal amplifier includes a first semiconductor optical amplifier having an input for receiving an optical signal, and an output, wherein the optical signal is amplified by the first semiconductor optical amplifier resulting in an amplified optical signal. The optical amplifier also includes an optical signal isolator having an input in optical communication with the output of the first semiconductor optical amplifier, and an output, wherein the optical signal isolator receives the amplified signal from the first semiconductor optical amplifier and allows for transmission of an optical signal in a single direction. The optical amplifier further includes a second semiconductor optical amplifier having an input for receiving the amplified optical signal from the optical signal isolator, and an output, wherein the amplified optical signal is amplified by the second semiconductor optical amplifier resulting in a twice amplified optical signal.

Abstract: A monitoring system useful for monitoring the state of a fiber communication channel in which a portion of the fiber signal is tapped and detected by a photodiode. The dark current of the photodiode and other DC offsets of the system may be compensated by passing a known signal through the photodiode and extracting the component due to the known signal. The known signal may be a locally generated optical signal having a predetermined harmonic signature. Optionally, the fiber signal may be selectively attenuated before being combined with the known signal so only the known signal is detected. The known signal may also be a dark signal induced by selectively attenuating the fiber signal. The system may include a temperature sensor which allows the compensation to be performed against stored temperature dependent compensation values while the fiber signal is not attenuated.

Abstract: An electrically controllable azimuth optical rotator (10) includes a first quarterwave plate (16) for receiving a first beam of electromagnetic energy (22) having a first arbitrary polarization state, and outputting a second beam (122) in response to the first quarterwave plate (16). An electric voltage controlled ferro-electric variable phase retarder (20) aligned at approximately 45 degrees to the first quarterwave plate (16) receives the second beam 122 and provides a third beam 38 in response to the retarder (20). The electric voltage controlled ferro-electric variable phase retarder (20) is characterized by a phase shift of &phgr;=2&agr;, where &agr; is a desired angle of rotation of the first arbitrary polarization state. To provide a voltage-controlled rotation, a second quarterwave plate (18) is aligned either parallel or perpendicular to the first quarterwave plate (16) for receiving the third beam (38) and outputting a fourth beam (46) in response to the retarder (20).

Abstract: To produce a fiber laser (106) a double-cladding active fiber (114) doped with Yb is predisposed to receive, near a first end (114a), a UV radiation suitable to write a first Bragg grating; during the writing process, a scanned pumping radiation is fed to the first end of the active fiber in order to excite an amplified stimulated emission between the first grating and the reflecting surface of a second end (114b) of the active fiber, previously cut and cleaned, and to consequently induce a laser emission from the active fiber; the optical power of the laser emission is measured and processed to obtain the laser efficiency; when a maximum value of the efficiency is reached, the writing process is stopped; similar steps are used to write a second grating near the second end (114b) of the active fiber.

Abstract: A multi-wavelength Raman laser comprising a Raman fiber forming part of an optical ring, preferably most parts of which are formed by optical fiber. The ring includes a periodic filter selectively transmitting optical power at a number of equally spaced wavelengths corresponding to the wavelengths of the laser output. Radiation at the signal wavelengths propagating in one direction on the ring is tapped onto an output fiber. An optical isolator is formed either in the ring or fiber tapped into the ring to suppress radiation propagating in the reverse direction on the ring. A frequency shifter may be inserted into the loop to prevent power from concentrating in a single mode, thereby allowing wide band lasing. A band pass filter may be inserted into the loop to restrict the lasing band.

Abstract: A polarization mode dispersion center (306) measures PMD impairment through the cross-correlation of optical pulses. A second variable phase retarder plate (504) is oriented with polarization eigenstates at preferably 45 degree angle with respect to those eigenstates of a first variable phase retarder plate (502) to provide controllable phase retardations that can be varied and measured as an indication of PMD impairment.

Abstract: An integrated semiconductor device comprising a wavelength-tunable laser, such as a distributed Bragg reflector (DBR) laser, where the laser has a gain section that includes an active layer, and a grating section that includes an active layer and a current-induced grating. A first electrical contact is provided over the gain section to supply current to the gain section and control the output power of the light, and a second electrical contact is provided over the grating section to supply current to the grating section and control the wavelength of the emitted light. The current-induced grating of the present device causes gain in the active layer of the laser to be modulated spatially in the direction of light propagation, thus resulting in only one of the degenerate Bragg modes to oscillate. As the degeneracy of the Bragg modes is broken by current-injection, and not facet reflection, substantially continuous wavelength tuning is possible without the deleterious phenomenon of “mode hopping.

Abstract: A semiconductor pump laser comprises a ridge waveguide electro-optical structure, which converts a ridge injection current into light and an integrated wavelength selective facet reflector. This reflector controls the longitudinal modal operation of the pump laser. Specifically, the reflector comprises a first reflective structure for reflecting light to return through the ridge waveguide electro-optical structure. A second reflective structure provides wavelength-selective reflectivity when operating in combination with the first reflective structure. In other words, the phase of light reflected from the first and second reflective structures is such that the net reflectivity of the facet is wavelength selective, or favors certain wavelengths over other wavelengths.

Abstract: An apparatus is provided including a first chip having a plurality of solder bumps and recesses formed therein at preselected locations. A second chip is provided with a plurality of solder pads and projections. A plurality of solder bonds are coupled between the first and second chips. At least one of the recesses and projections includes angled walls for capturing and directing the other during reflow of the solder bonds such that the first chip aligns relative to the second chip under the surface tension of the solder bonds. If desired, vibrating waves may be applied to the first and second chips during reflow to assist movement of the projections relative to the recesses.

Abstract: A semiconductor laser having an external cavity including a single-mode optical fiber. A Bragg grating is written onto the fiber which defines the end of the optical cavity, selects the lasing wavelength, and discriminates against the lasing of higher-order transverse modes in the multi-mode gain region. In one embodiment, the semiconductor laser includes an optically active vertical-cavity semiconductor stack similar to a vertical-cavity surface emitting laser. The stack is optically pumped either from the front or the back over a relatively large area such a multi-mode beam is output. Optics couple the multi-mode beam to the single-mode input of the fiber. A partially transmissive mirror of reflectivity between 25 and 40% may be placed on the output surface of the semiconductor stack to form a coupled-cavity laser. A plurality of laser diodes can be angularly positioned around the area of the semiconductor stack being pumped to increase the total pump power.

Abstract: A method of forming a hybrid optical component includes the steps of masking and etching a pattern on a core layer of a planar optical component to define at least one alignment element and an optical element and subsequently overcladding the optical element such that a passive platform is formed which exposes a surface of the optical element such as a waveguide and an alignment element for receiving a mirror image alignment element formed on an active platform including an active device, such as a laser. Hybrid components include a passive platform having an alignment element formed therein and a waveguide for receiving an active platform with a mating mirror image alignment element and an active device which aligns with the waveguide when the platforms are mated.

Abstract: A method and a system are disclosed for reducing four-wave mixing (FWM) penalties in an optical transmission network. The FWM penalties are reduced by simultaneously and periodically modulating the phase of the optical signals propagating through a long fiber waveguide at a modulation frequency that causes destructive interference of the FWM products that are otherwise generated along the length of the long fiber waveguide. The method may be implemented in an optical transmitter for an optical transmission network by providing a phase modulator between the multiplexer and an optical boost amplifier so as to simultaneously modulate the phase of all the optical signals that are transmitted through the long fiber waveguide. Alternatively, a phase modulator may be disposed between each source of modulated optical signals and the multiplexer so as to separately modulate the phase of all the optical signals that are subsequently transmitted through the long fiber waveguide.

Abstract: An optical switch is provided. The optical switch includes a substrate having a first surface and a second surface. At least one optical waveguide is formed below the first surface of the substrate. A heating element is disposed on the first surface of the substrate. The heating element is also disposed in proximity to the at least one optical waveguide. A cavity is formed in the second surface of the substrate. The cavity is also disposed in the proximity to the at least one optical waveguide. A heat conductive material is disposed within the cavity.

Abstract: An optoelectronic module includes a ceramic waferboard having a groove configured to passively position an optical fiber. The ceramic waferboard includes an alignment feature configured to passively position an optical component. An optical device is secured to the ceramic waferboard in contact with the alignment feature to thereby position the optical device. An optical fiber is positioned in the groove with an end of the optical fiber positioned adjacent the optical device to thereby optically couple the optical fiber to the optical device. The optoelectronic module also includes an integrated circuit chip secured to the ceramic waferboard, and a conductive material disposed on the ceramic waferboard and electrically coupling the integrated circuit chip to the optical device.

Abstract: An optical fiber collimator (100) in an optical system, includes a pair of optical fibers (108) having emitting cleaved planes (112) to provide a substantially uniform angled side surface for forming a prescribed angle (101) relative to the optical axis (105) of the optical system. The pair of optical fibers (108) are disposed coplanarly in the object plane of the optical system for sharing the optical axis and separated from each other and from the optical axis on the same object plane. Optically coupled to the pair of fibers, a microlens (106) has a sloped rear surface (114) opposite a rotationally symmetric microlens surface (116) which bound a volume having a homogeneous index of refraction. The pair of fibers (108) are positioned near the focal plane containing the optical axis (105) of the microlens for the generation or reception of collimated beams at the prescribed angle (101) relative to the optical axis (105) of the microlens (106).

Abstract: A gain-tunable semiconductor optical amplifier (10) includes an amplifying section (38) for amplifying an optical signal (422). A first tunable reflector section (51) and a second tunable reflector section (52) are integrated on opposed sides of the amplifying section (38) to reflect the optical signal at a clamping wavelength and to change an internal gain level to cause a stimulated emission at the clamping wavelength above the internal gain level.

Abstract: A process for fabricating a solder bump (113) includes providing an inorganic de-wetting substrate (102). In order to form a composite substrate (20), having the desired wetting/dewetting composition, a wetting metal is first applied on the inorganic de-wetting substrate to create at least one wetting metal pad (52). The composite substrate (20) is then dipped or otherwise immersed into a reservoir of liquid solder (106). Next, the composite substrate (20) is redrawn (116), or otherwise removed, from the liquid solder to form solder bumps (113) on the at least one metal wetting pad (52).

Abstract: An optical device including an optical amplifier to amplify optical signals received through an optical input, and to supply the amplified optical signals from an optical output, and an optical filter component to compensate for variations in the gain spectrum of the optical amplifier that occur as a function of wavelength and operating temperature. The optical filter component includes a first optical filter having an athermalized transmission spectrum and a second optical filter having a transmission (or insertion loss) spectrum that varies as a function of operating temperature.

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.