Abstract:
An amplitude-modulated vestigial-sideband, television channel sub-carrier multiplexed optical fiber transmission system includes a laser diode operating linearly throughout the desired range of multiplex frequencies. Such linear laser diode operation is accomplished by limiting leakage current within the laser diode to a very low level. The composite second-order distortion in the optical output signal from the laser diode is down typically 50 db from the video carrier for each channel. For some laser diodes that exhibit slow turn-on in the L-I characteristic, there is a point of inflection in the L-I curve. Operation with the laser biased at or near this point results in extremely linear performance, even though the laser may have insufficient blocking of leakage current to otherwise produce acceptable linearity.
Abstract:
The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.
Abstract:
An apparatus is presented in which a sample can be accurately repositioned in a spectroscopic and/or imaging apparatus upon multiple insertions, and where the apparatus can be worn by living subjects for extended periods of time. The apparatus additionally reduces the temperature increase and stabilizes the temperature of the sample upon irradiation with an optical source of excitation. Additionally, the apparatus stabilizes the pressure and critical optical properties of the sample and its interface with the apparatus. Alternatively or additionally, the apparatus can be used to alter and/or substantially reduce fluorescence from targeted fluorophores in the sample.
Abstract:
This disclosure concerns systems and devices configured to implement impedance matching schemes in a high speed data transmission environment. In one example, an optoelectronic assembly is provided that includes a TO package having a base through which one or more leads pass. The leads are electrically coupled to an optoelectronic device in the TO package, and are electrically isolated from the base. Some or all of the leads include a ground ring that is electrically isolated from the lead and electrically coupled with the base. A circuit interconnect is also included that is electrically coupled to the optoelectronic device and the TO package. The circuit interconnect includes a dielectric substrate having signal traces that are electrically coupled to the signal leads. A ground signal conductor disposed on the dielectric substrate is electrically coupled with the ground rings.
Abstract:
A semiconductor avalanche photodiode (APD) with very high current gain utilizes a small vacuum or gas filled gap which is used as a region to accelerate electrons to high energies. The APD has an absorption layer, a gap, and a multiplication layer. The absorption layer is adapted to generate electron-hole pairs upon absorbing light. The APD is adapted to generate an electric field in the gap and at an interface between the absorption layer and the gap. The electric field extracts electrons from the absorption layer into the gap and accelerates the extracted electrons while in the gap. The multiplication layer is adapted so that said accelerated electrons impinge on and cause a flow of secondary electrons within the multiplication layer.
Abstract:
A method of maintaining desirable optical performance of optical emitters over temperature variations is disclosed. The optical performance of an optical emitter in terms of power, extinction ratio, jitter, mask margin and general fiber optic transmitter eye quality can be maintained by the present invention over a wide range of temperatures. Advantageously, the present invention enables the use of inexpensive optical emitters in optoelectronic transceivers and optoelectronic transmitters.
Abstract:
Manufacturing coupling elements that have two or more ports. A focusing lens array is attached with a collimating lens array to form an element array such that each focusing lenslet is opposite a collimating lenslet. Optionally, an optical element such as a beam splitter is included between the focusing lens array and the collimating lens array. The individual coupling elements are then cut from the element array. After a row of coupling elements is cut or separated from the element array, a side of the exposed optical element can be polished and a third row of lenslets can be attached to the polished side of the optical element before the row is cut into individual coupling elements. This provides a third port to the coupling elements or optical transceivers.
Abstract:
A Semiconductor Optical Amplifier (SOA) with extended bandwidth and the method of fabricating the same are disclosed. In one embodiment, the SOA includes a Multiple Quantum Well (MQW) stacks whose thickness varies along the length of the device. The SOA has a flatter and broader gain spectrum than SOAs with substantially flat MQW stacks.
Abstract:
A tunable vertical cavity surface emitting laser (VCSEL) using photonic crystals and an electrostrictive material that includes a hologram with a narrow filter function. Photonic crystals are formed such that the active region of the VCSEL is bounded by the photonic crystals. The photonic crystals have a periodic cavity structure that reflects light of certain wavelengths through the active region of the VCSEL such that laser light at the wavelengths is generated. The periodic cavity structure includes a central defect that does not include any cavities. The single mode is emitted through the central defect. The electrostrictive material that includes a hologram makes the VCSEL tunable because the shape of the electrostrictive material changes when an electric field is applied. The filter function of the hologram thus changes as well in response to the electric field such that the VCSEL is tunable.
Abstract:
An optical assembly includes a first lens positioned along a first axis and configured to focus light from a light source along the first axis, and a second lens positioned along the first axis and configured to focus light from the first lens onto an optical target. A third lens is positioned along a second axis and configured to approximately collimate light from a second light source along the second axis, and a reflector positioned along the second axis is configured to reflect light from the third lens onto a fourth lens. The fourth lens is positioned on a third axis angled from the second axis and configured to focus light from the reflector onto an optical detector. Furthermore, the optical assembly is preferably a single molded optic. The optical assembly may be used in an optoelectronic transceiver having an optical subassembly, including a light source and an optical detector. The optical assembly is used to couple a pair of closely spaced optical fibers to the light source and optical detector.