Abstract: A method and a system for monitoring specific channels in a WDM system involve splitting a WDM signal into multiple parallel signals, filtering the parallel signals with corresponding individually tunable filters in order to pass specific channels to each filter, and then detecting the presence of passed channels with dedicated detectors that correspond to the tunable filters. In a preferred embodiment, the initial WDM signal is demultiplexed by wavelength into multiple different transmission groups and each filter can be individually tuned over a channel range that corresponds to the range of channels within the transmission group that is directed to the filter. The preferred individually tunable filters are vertical cavity filters formed utilizing semiconductor wafer processing techniques, and the preferred photodetectors are simple low cost single-cell photodetectors.

Abstract: The optical switch comprises a substrate, a planar waveguide circuit, an index-matching liquid, a working fluid and a displacing device. The planar waveguide circuit is supported by the substrate. The planar waveguide circuit and the substrate collectively define a trench that includes a first trench region and a second trench region adjacent the first trench region. The second trench region has a width greater than the first trench region. The planar waveguide circuit includes a first waveguide and a second waveguide. The waveguides intersect at the first trench region and are positioned such that light traversing the first waveguide enters the second waveguide when an index-matching material is present in the first trench region, and is otherwise reflected by said the first trench region. The index-matching liquid is located in at least part of the first trench region. The working fluid is located in the second trench region.

Abstract: A laser source (10, 30, 40) comprising a laser medium (10) having a back facet (10B) and a front surface (10A), whereby the laser medium (10) is adapted to emit a laser beam through the front surface into an external cavity defined in length by a cavity end mirror (40) reflecting the laser beam back towards the laser medium (10). A wavelength tunable filter (30) is arranged between the laser medium (10) and the cavity end mirror (40) adapted for tuning the wavelength of the laser beam. The laser medium (10), the wavelength tunable filter (30), and the cavity end mirror (40) are arranged in a spatially linear cavity structure substantially in a line without angular redirection of the laser beam in the cavity between the laser medium (10) and the cavity end mirror (40).

Abstract: An optical arrangement (10, 30, 40) for direction dependent coupling out of light comprises a first (10) and a second (40) polarization converter each for converting the state of polarization of light received in a predetermined way. A polarization dependent coupling device (30) is adapted for coupling out a portion of the light received, whereby the ratio of the coupled out portion substantially depends on the state of polarization of the light received. The polarization dependent coupling device (30) is arranged between the first (10) and the second (40) polarization converters, and the optical arrangement (10, 30, 40) receives from different sides light beams propagating in different directions. The characteristics of the first (10) and the second polarization converters (40) are adapted that the polarization dependent coupling device (30) receives light beams propagating with different states of polarization in the different directions.

Abstract: A filter (20) is provided for injecting data dependent jitter and level noise into a digital data signal (1) with a given data rate (A). The filter (20) reacts on a step function with a step response (2) showing after a first increase or decrease (B) a substantial extreme value (C), such as a minimum or a maximum, of opposite direction than the first increase or decrease. The temporal occurrence of the substantial extreme value (C) with respect to the step function is substantially in the range of the given data rate (A).

Abstract: The invention relates to a flow divider (20) and a process for dividing a fluid flow (30) into a number of fluid flows (31, 32), in particular in analytical and/or preparative fluid measurement technology and/or in micro-fluid systems. The flow divider (20) exhibits at least one working sensor (41, 42), which is assigned to one of the fluid flows (31, 32) and which comprises a control unit (55) for regulating the pressure of one of the fluid flows (31, 32) and/or for regulating one of the fluid flows (31, 32), which is coupled to the or each working sensor (41, 42) and an actuator (51) for changing this fluid flow (31). At least a number of working sensors (41, 42) corresponding to the number of divided fluid flows (31, 32) is provided, whereby respectively at least one of the working sensors (41, 42) is assigned to one of the fluid flows (31, 32) and whereby the working sensors (41, 42) enable recording of the respective fluid flow (31, 32).

Abstract: An optical resonator receives a light beam having a first state of polarization. The resonator comprises a polarization modifying device (40) and a polarization dependent coupling device (30) for coupling light having the first state of polarization into a first path and for coupling light having a state of polarization perpendicular to the first state of polarization into a second path. The polarization dependent coupling device (30) is arranged to receive from a first propagation direction the light beam having the first state of polarization and to couple the light beam from the first propagation direction in the first path to the polarization modifying device (40). The polarization modifying device (40) is arranged for modifying the state of polarization of the light beam before reentering the first path of the polarization dependent coupling device (30) from a second propagation direction in order to couple into the second path a portion of the light beam traveling into the second propagation direction.

Abstract: To provide a stabilised current to a current modulator or the like in a limited voltage headroom environment, the present invention supports a current mirror having first and second mirror transistors (34, 36). Bases of the transistors are coupled together through a resistive element (R1, 102), with base leakage current (Ibase) to the first transistor generating a voltage drop (IbaseR1) across the resistive element (R1, 102). The voltage drop acts to boost a voltage through an emitter resistor (R3) of an output stage of the current mirror, the output stage realised by at least the second mirror transistor (36). With boosting of the voltage through the emitter resistor (R3) there is a corresponding boost in output current (Iout, 52) defined by the voltage across emitter resistor (R3).

Abstract: A variable gain amplifier stage has first and second input terminals for receiving a differential input signal and first and second emitter follower transistors having their base electrodes coupled to the input terminals and their emitter electrodes coupled to a pair of matched voltage controlled current sources. A differential pair of transistors has their base electrodes coupled to the emitter electrodes of the first and second emitter follower transistors and their emitter electrodes coupled together and to a third voltage controlled current source. The voltage controlled current sources are controlled by the same voltage source so that a decrease in the differential pair tail current increases the bandwidth and decreases the gain of the stage, but a decrease in the current through the emitter follower transistors decreases the bandwidth of the stage so that by carefully controlling the relationship between these currents, a constant bandwidth can be maintained.

Abstract: A probe apparatus for use with analyzing devices, primarily oscilloscopes and logic analyzers, which uses pole-zero cancellation to provide a probe with low capacitance and wide bandwidth. Pole-zero cancellation enables the probe to have constant gain at all frequencies. In one embodiment, the coaxial cable between the probe tip and the replication amplifier is terminated in its characteristic impedance to provide constant gain at all frequencies regardless of cable length. Use of pole-zero cancellation and thick film technology enables building a probe with a small, durable tip.

Abstract: A laboratory microchip includes a carrier with a micro spray tip projecting vertically out of a plane of the carrier. The carrier and spray tip are designed as a monolithic or single unit. The spray tip includes a passage channel which conveys the substances to be sprayed from a channel to a spray tip aperture. The channel is a part of a channel structure which is enclosed to the outside by a cover plate. The spray tip includes, on the sides of the spray aperture, an area which tapers conically inwards. Connected to this tapered area is a constant cross-section drill hole forming an annular internal step formation at the transition between the two areas. The outer diameter of the conically tapering tip is locally reduced in proximity to the aperture to provide a finer tip to the spray tip. The finer tip increases the electrical fields occurring at the tip, to further increase the forces which act on the substances and for dispersion spraying.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricated on a substrate by mass loading piezoelectric (PZ) layer between two electrodes. For a substrate having multiple resonators, only selected resonator is mass loaded to provide resonators having different resonance frequencies on the same substrate.

Abstract: Functional testing of complex digital integrated circuits. A complex integrated circuit such as a system-on-a-chip (SOC) designed using high-level tools is tested by decomposing it into functional blocks wrapped by scan path cells. A tester which includes a field programmable gate array (FPGA) or similar device is connected to the SOC to be tested, and a simulation model of a chosen functional block of the SOC selected for test is loaded into the FPGA. A test pattern is applied to the functional block of the SOC using the scan path cells, and to the FPGA simulation. The FPGA may be rapidly reconfigured to test other functional blocks of the SOC.

Abstract: An inner control loop controls the relative position of a surface to be scanned with respect to a focal plane. An outer control loop responds to the location of the surface to be scanned with respect to a focal plane of the scan lens to generate a setpoint for the inner control loop. A sample-and-hold element disposed between the inner and outer control loops is switched by an edge or defect detector. It is preferred that the outer control loop has a time constant in the range of three to ten times longer than that of the inner control loop. The sample-and-hold element provides a gradual state transition upon the occurrence of an edge or a surface defect.

Abstract: A light emitting device and photodetector combination having a structure in which the layer of the photodetector that contacts the light emitting device is separated from the light emitting device by a native semiconductor oxide layer that is both insulating and has a refractive index lower than that of the light emitting device and the photodetector. This configuration results in a light emitting device and photodetector structure that minimizes the capture of the spontaneous emission light output from the light emitting device by the photodetector while electrically isolating the light emitting device from the photodetector. The electrical isolation of the light emitting device from the photodetector results in a four terminal device in which the light emitting device and photodetector may be independently biased, and can therefore be operated at a very low bias voltage.

Abstract: Highly purified, porous silica microspheres contain functional groups which are capable of selectively binding to reaction impurities, such as excess reactant or reaction by-products, which are contained in a reaction medium. The reaction impurities can thereby be efficiently removed from the reaction medium, providing a convenient method for product purification.

Abstract: A data communications signal conforming to the SDH/SONET hierarchy of data structures is analysed to determine the structure to which it conforms. Payload pointers within the signal are extracted and interpreted to establish their status. The pointer statuses are grouped and analysed, enabling the structure of the payload data to be established. The structure of the data signal may be displayed in a format which conveys the information concisely, and facilitates detailed investigation of individual characteristics of the data signal.

Abstract: A system and method of digitizing characteristic parameters of a quasi-sinusoidal analog signal of unknown magnitude, frequency and phase-offset, includes digitizing the analog signal at a first sampling rate, thereby generating a plurality of sets of digital signal waveform samples. Successive sets of the digital signal waveform samples are digitally processed to generate continually updated digital characteristic parameters representing a characteristic behavior of the quasi-sinusoidal analog signal.

Abstract: An optical switch includes a core and a fluid reservoir. The core includes a base, a matrix controller substrate, and a planar lightwave circuit. The planar lightwave circuit has a plurality of waveguides and a plurality of trenches. Each trench is located at an intersection of two waveguides. The fluid reservoir supplies a fluid to the plurality of trenches of the core. The optical switch further includes a getter for removing atmospheric gases from the fluid. The getter may be a porous silica getter, a non-evaporable getter, or an evaporable getter. By removing atmospheric gases from the fluid, the getter improves the capacity and operation of the optical switch. The optical switch may further include a membrane to separate the getter in a getter chamber from the fluid in a fluid chamber.

Abstract: A method and system for automatic negotiation of maximal shared data transmission and reception rates by fibre channel nodes in a fibre channel arbitrated loop. An auto-speed-negotiation function is included in the fibre channel arbitrated loop initialization procedure. A fibre channel node undergoing initialization turns off its transmitter in order to elicit a loss of synchronization condition in the next fibre channel node of the arbitrated loop. Upon detection of loss of synchronization, each subsequent fibre channel arbitrated loop node invokes the auto-speed-negotiation function. The fibre channel node then turns its transmitter back on at the highest possible data transmission rate, sets the data reception rate of the fibre channel node's receiver to the lowest possible data reception rate, and then waits to detect word synchronization by the receiver.