Abstract: Disclosed is a microfluidic sensor complex structure comprising a lower plate, a middle plate and an upper plate. A reference electrode, a working electrode and an electrode connection are formed on the lower plate. The middle plate comprises a microfluidic channel passage therein. The upper plate is overlaid on the middle plate so as to induce a capillary phenomenon on the microfluidic channel passage formed on in the middle plate. The microfluidic sensor complex structure allows the motion of a sample to be driven only by a capillary phenomenon, without additional operation, and allows an immune response, washing, and electrochemical analysis in one round once a sample is introduced thereinto. Hence, it requires only a short time period for measurement, is convenient to handle, and shows sensitivity and selectivity. Also, it can be produced on a mass scale because it can be formed of typical organic polymers using a simple method.

Abstract: Disclosed is a microfluidic sensor complex structure comprising a lower plate, a middle plate and an upper plate. A reference electrode, a working electrode and an electrode connection are formed on the lower plate. The middle plate comprises a microfluidic channel passage therein. The upper plate is overlaid on the middle plate so as to induce a capillary phenomenon on the microfluidic channel passage formed on in the middle plate. The microfluidic sensor complex structure allows the motion of a sample to be driven only by a capillary phenomenon, without additional operation, and allows an immune response, washing, and electrochemical analysis in one round once a sample is introduced thereinto. Hence, it requires only a short time period for measurement, is convenient to handle, and shows sensitivity and selectivity. Also, it can be produced on a mass scale because it can be formed of typical organic polymers using a simple method.

Abstract: An apparatus and method are provided for amplifying a signal having several multiplexed channels of different wavelengths. In one embodiment, an amplifier 100 is provided having a doped fiber 120 coupled to an input 105, a pump 145 coupled to the doped fiber to provide an output to amplify the signal therein and a control system 130 for controlling the pump. The control system 130 has a detector 170 for measuring power of the signal and a controller 180 for adjusting power to the pump 145 based on predetermined criteria and the measured signal power. The pump power is adjusted as a linear function of the signal power by including within the predetermined criteria a multiplier by which the signal power is multiplied, and an offset that is added to the product of the multiplier and the signal power to ensure that the power applied to the pump 145 is non-zero even for zero signal power.

Abstract: A four-port Wavelength-Division-Multiplexing (WDM) element is disclosed that can be employed for various purposes in optical communication networks, particularly in bi-directional fiber optic lines. In one embodiment, one four-port WDM element is used with one optical amplifier to provide bi-directional propagation on the same fiber. In another embodiment, the four-port element is used in conjunction with optical attenuators to provide for gain equalization of channels and the flexibility to add or remove channels. In yet another embodiment, input and output ports are added to current-art elements thereby enabling bi-directional operation to be achieved with equipment that does not provide such capabilities.

Abstract: A differential method of improving the carrier to noise ratio of optically transmitted amplitude modulated signals without affecting the fidelity of the transmitted signals is disclosed. The disclosed method improves over prior art methods by utilizing a single transmission fiber transmitting two wavelengths that are modulated out of phase by a single Mach Zehnder type modulator. The received light is separated into two components at two wavelengths and each wavelength is received by a photodetector. The two photodetector outputs are differentially combined to produce an output with improved signal to noise ratio resulting in improved bit error rates in digital transmissions. The invention is also useful in fiber optic analog transmission systems such as those used to distribute AM-VSB Cable Television programming, wherein the differential method improves the carrier to noise ratio without increasing the nonlinear components in the signal.

Abstract: An improved method of measurement of noise figure and gain of optical amplifiers is based on transforming the amplifier into an oscillator by applying optical feedback with known loss. The feedback consists of a tunable filter for wavelength control and of a variable attenuator for gain control. Measuring the output power at a given wavelength and the noise characteristics of the output signal, either with an optical spectrum analyzer or with a set of tunable filters and a power meter, provides data for full characterization of the optical amplifier. Another method is disclosed that utilizes the self-heterodyne setup and electrical spectrum analyzer to measure the spectral line width of the lasing amplifier, from which the noise figure is derived.

Abstract: One method of determining the signal to noise ratio of an optical signal models the noise floor based on amplified spontaneous emission (ASE) which is accumulated along the link. The ASE wavelength dependence is represented by a known mathematical function with a limited number of parameters. The parameters of this function are derived from measurements of the noise floor at a limited number of points by computational best fit means. A number of fiber grating filters at wavelengths between ITU allocated wavelengths are used to sample the optical noise and reflect the light back. An optical circulator is used to direct the reflected ASE light to an optical switch which allows the detector to select between transmitted and reflected light. The signal transmitted through the switch is monitored by a scanning filter with the appropriate resolution to resolve the signal or noise peaks. A first scan of the transmitted peaks is carried out and the signal is digitized and stored.

Abstract: A bidirectionally amplifying rare earth doped fiber optical amplifier having an equalized gain at multiple wavelengths is disclosed for use in dense wavelength multiplexed bidirectional fiber transmission applications. In a first embodiment, a four port circulator is utilized with two amplifying fibers; one for each direction of propagation and a multiplicity of gratings configured to equalize the gain at the different wavelengths. Different embodiments utilizing three port and four port circulators are utilized. A more general amplifier device with equal gain at multiple wavelengths is disclosed.

Abstract: A system and method are disclosed for adjusting the gain profile of an optical amplifier including a pump laser and an active gain element by selectively controlling the electron populations of at least one Stark sublevel of the electronic energy levels of the optical amplifier's active gain element. By dynamically controlling the electron populations of selected Stark sublevels the gain profile of the active gain element can be flattened. In a first method for controlling electron populations two-photon transitions are initiated between a pair of Stark sublevels of the same energy manifold of the active gain element. Two-photon transitions are stimulated by two additional pump lasers operating at wavelengths whose difference approximates the energy difference in the pair of Stark sublevels between which electrons are to be moved.