Abstract: An optical sub-system is disclosed which includes an embedded digital processor for providing continuous monitoring and adjusting of various operating parameters associated with the sub-system. The ability to modify various parameters such as bias voltage, optical signal power, etc., as a function of changes in the environment (e.g., ambient temperature, device age, power supply) results in optimization of the sub-system. The digital processor is initially programmed during environmental testing in manufacture to provide a memory associated with the digital processor which includes the optimal values for a preselected set of operating parameters as a function of various environmental conditions.

Abstract: A method for providing an essentially uniform coating over the outer surface of an article of manufacture. In particular, a vapor deposition process is disclosed for coating relatively small articles, such as spheres which may be used as lenses in optical systems. The coating may comprise an anti-reflective or alternatively, reflective, material.

Abstract: An objective lens for a free-space photonic switching system is disclosed. The objective lens is utilized to change a collimated array of beams into an array of spots which will focus on the array of spatial light modulating elements (S-SEEDs, for example). The requirements for the lens (low f-number, field of view, etc.), result in a lens which includes an external stop, positive doublet, a positive (e.g., plano-convex) lens and a negative (e.g., field flattener) lens, the latter pair of lenses being separated by a predetermined distance d.

Abstract: An optical packaging arrangement is disclosed which utilizes silicon technology and overmolding techniques to provide a single in-line package with completely passive alignment between the various optical components. The technique as disclosed is useful in the packaging of a single active optical device and associated electronics, a pair of optical devices and electronics (transceiver), or an array of any desired number of such components. Since the silicon may be processed to include etched alignment fiducials and metallized bond pad sites, solder bump self-alignment and silicon optical bench technology may be used to provide for alignment between the active device, coupling lens and associated optical fiber.

Abstract: A method for processing a leadframe for use with a molded package is disclosed. In particular, the method is suited for arrangements where direct wirebond attachment sites are exposed through the molding material. Conventional molding processes usually result in leaving a residue of molding material on the exposed wirebond sites. The invention is directed to including a protective layer of material over the wirebond locations during the leadframe plating operation. The protective layer (and any molding residue covering the protective layer) may then be removed using an etchant after the molding operation, exposing the underlying wirebond contact sites.

Abstract: A method is disclosed for determining the byte error rate (ByER) of a received digital signal. In particular, a local byte clock signal is generated and a complement of the received signal (or clock signal) is compared to the clock signal (or received signal). When both are the same logic value, as determined by a series of logic gates, an error is deemed to have occurred. The total number of errors N over a predetermined period of time T are then counted.

Abstract: An optical package particularly suited for use with a pair of optical devices is disclosed. In a preferred embodiment, the package may house an optical transmitting device and an optical receiving device such that the package forms a transceiver. The package advantageously utilizes a number of molded plastic piece parts to reduce the package cost and simplify construction. By utilizing molded components, optical alignment within the package is automatically achieved.

Abstract: An optical sub-system is disclosed which includes an embedded micro-controller for providing continuous monitoring and adjusting of various operating parameters associated with the sub-system. The ability to modify various parameters such as bias voltage, optical signal power, etc., as a function of changes in the environment (e.g., ambient temperature, device age, power supply) results in optimization of the sub-system. The micro-controller is initially programmed during environmental testing in manufacture to provide a memory within the micro-controller which includes the optimal values for a preselected set of operating parameters as a function of various environmental conditions.

Abstract: An arrangement for providing improved efficiency in laser bonding is disclosed. In particular, at least one piece part in the arrangement is formed to include means for concentrating a beam of radiation at a predetermined attachment location (or several locations). The concentrating means may be in the form of an aperture, such as a conical or parabolic opening, which will concentrate the radiation to the area of interest. Alternatively, if the piece part is transparent to the wavelength of the radiation, the concentrating means may be in the form of a lens or grating formed on the surface of the piece part.

Abstract: A spherical multicomponent optical isolator having a first spherical segment lensing region, including a base, a second spherical segment lensing region, including a base, a first polarizer attached to the base of the first segment lensing region, a second polarizer attached to the base of the second spherical segment lensing region and A Faraday rotator disposed between the first and second polarizers, wherein the combination of the first and second spherical segments, the first and second polarizers and the Faraday rotator forms the spherical optical isolator having a spherical outer surface.

Abstract: A novel optical subassembly arrangement is proposed. The subassembly comprises a silicon-based submount including a plurality of openings for placement of the various optical components utilized to form the optical subassembly. In particular, a silicon wafer is processed (e.g., etched) using conventional techniques to simultaneously form a large number of individual submounts, each submount processed to include a number of openings. The silicon processing may be sufficiently controlled such that active alignment of the components is minimized. An important feature of the design, when associated with an isolated embodiment, is that the silicon submount is formed to include openings for both the laser and isolator optics such that the openings are disposed along a thermal transport path through the silicon substrate from an attached thermoelectric cooler (TEC). Therefore, the laser and isolator optics are maintained at the same operating temperature.

Abstract: An optical subassembly is disclosed which provides self-alignment between an active optical device and associated optical elements. In particular, the subassembly comprises a first substrate member which is utilized to support the active optical device. A separate plurality of substrate members is used to form a support for the associated optical elements (i.e., fiber, coupling lens or both), where the separate members are stacked, one on top of the other, and an aperture through the center thereof utilized to support the optical elements. The aperture may be formed to include a mechanical stop suitable for fixing the location of an optical fiber endface. Alignment fiducials formed on the device support member and the stack provide self-alignment therebetween, as well as physical attachment of the support member to the stack. The various substrate members may comprise any suitable material including, but not limited to, silicon, metal, or molded plastic.

Abstract: An optical subassembly is disclosed which provides for passive alignment between an active optical device, lens and optical fiber. A first substrate is used as a mount for the active optical device and a second substrate is formed to include an aperture designed to capture the lens. Alignment fiducials formed on the mating surfaces of the first and second substrates provide accurate optical alignment between the active device and the lens. An optical fiber receptacle is formed to mate with the optical header supporting the substrates and thus provide alignment between the optical fiber and the active device/lens configuration. Preferably, the receptacle is formed to prevent physical contact with the aligned substrates, so that any movement of the receptacle will not effect the alignment between the device and lens.

Abstract: A balanced doped fiber optical amplifier is disclosed which requires only a single wavelength division multiplexer to provide pump and signal inputs to multiple amplifier stages. In particular, a first section of doped fiber is coupled to an "input" port of the multiplexer and a second section of doped fiber is coupled to an "output" port of the multiplexer. First and second pump signals are coupled to the remaining ports to provide a counter-propagating pump signal to the first doped fiber section and a co-propagating pump signal to the second doped fiber section. The parameters of each doped fiber section (e.g., length, dopant concentration, pump power, pump wavelength) may be individually tailored to provide the desired results (pre-amplification or power boosting, for example). A plurality of balanced optical amplifiers may be cascaded to provide multi-stage amplifiers, and the pump signal levels may be controlled to provide gain equalization.

Abstract: A laser diode structure including compensating elements for improving the linearity of the laser response, of particular concern for broadband analog applications. The compensation comprises voltage-dependent elements which are incorporated to correct for the presence of parasitic, voltage-dependent resistive and capacitive elements associated with the laser diode junction. These parasitic elements have been found to be a cause of the laser's nonlinear L-I relationship. By careful choice of the bias voltages supplied to the compensating elements, the nonlinearity due to the presence of the parasitic elements may be minimized. In particular, a combination of a voltage-dependent resistance and voltage-dependent capacitance may be utilized.

Abstract: An optical package for use with a laser diode in high speed applications. The package comprises a metallic housing with a multilayer ceramic (MLC) insert disposed through a sidewall thereof. The MLC insert is utilized to form a microstrip transmission line of a bandwidth sufficient to couple a high frequency signal source to the laser. A number of conductive vias are disposed through the thickness of the MLC insert at the package wall to serve as electric field shorts within the insert and improve the frequency response of the microstrip. A pair of such MLC inserts may be disposed through opposing sidewalls of the package and used to provide a conventional "butterfly" configuration, while preserving the integrity of the microstrip interconnection.

Abstract: An externally modulated laser-based transmitter is disclosed which utilizes an automatic bias control (ABC) circuit to maintain the bias voltage applied to the external modulator at a predetermined level required to provide the necessary separation between logic levels. The ABC circuit generates a dither signal and functions to digitally compare the phase of the dither signal to the phase of the optical signal produced by the external modulator. A phase comparator (e.g., D-type flip-flop) is used to monitor any drift in the optimum bias point of the modulator and generate an output correction signal by continuously adjusting the level of the DC bias voltage applied to the external modulator.

Abstract: An optical isolator is disclosed which comprises a Faraday rotator disposed between a pair of polarization selective elements (e.g., linear polarizers, birefringent wedges, birefringent plates, etc.). Improvement in isolation stability as a function of variations in temperature and/or signal wavelength are achieved in accordance with the teachings of the present invention by utilizing a Faraday device with a rotation .theta. less than the conventional 45.degree.. A linear reduction in .theta., while resulting in a some signal loss, provides a linear increase in both temperature and wavelength stability.

Abstract: A process for forming a dielectrically isolated wafer is disclosed. In particular, the conventional process is altered to replace the step of growing the thick polysilicon handle layer with the steps of growing a relatively thin conformal coating layer and bonding a single crystal wafer thereto. The wafer will become the substrate of the final device structure. The process of bonding is considered to be more efficient and economical than the prior art polysilicon growth process. Additionally, the tub structures of the wafer bonding process may be exposed to a somewhat lower temperature (for bonding) for shorter period of time than the tub regions of the conventional thick polysilicon DI structures. Therefore, the tub regions will exhibit superior qualities (e.g., less stress, fewer crystal defects) when compared with those formed with the conventional polysilicon growth technique.

Abstract: Apparatus and method are disclosed for providing the transfer of a semiconductor wafer from a first to a second location. The apparatus includes a transfer arm including a plurality of apertures to facilitate the attachment of a bowed wafer, without breakage or frontside contact, to the transfer arm. The size, number and location of the apertures may be determined in accordance with the size of the wafer, the amount of bow, as well as the type of bow (i.e., simple or complex). A plurality of flexible members may be disposed in a one-to-one relationship with the apertures and utilized to achieve a secure vacuum seal of the wafer to the transfer arm.