Abstract: A method and apparatus for stabilizing the wavelength of a laser are disclosed. The invention provides a way to stabilize a laser for applications in dense wavelength division multiplexing (DWDM) systems where frequency spacing is crucial. The invention accomplishes laser stabilization by generating one or more optical paths which are passed through one or more filters to obtain one or more signals which are a function of frequency. Another optical path which does not contain a filter is generated to obtain a signal which is a function of power. The frequency signal(s) and the power reference signal are then converted from optical to electrical and from analog-to-digital. A microcontroller is then used to normalize one or more selected frequency paths with respect to the optical power path, process the signals via software code, and generate a signal which provides feedback to the laser for stabilization.

Abstract: The invention in accordance with one aspect is a method of determining aging of a light emitting device which is capable of selectively emitting light having different wavelengths corresponding to different channels for light transmission as a function of tuning current supplied to the device. A tuning current is applied to the device which results in a wavelength corresponding to a desired channel. The slope of a curve which is light power from the device as a function of tuning current is determined by dithering about the applied tuning current. The determined slope is compared with a prior determined value in order to detect any change from the prior value. The voltage derived from a light signal passing through an optical filter can also be measured and compared to a prior value. These values may be used to determine aging of the device and the filter.

Abstract: A circuit for increasing the signal-to-noise ratio in an optical communication system and for stabilizing a laser wavelength. The circuit includes an impedance element disposed in parallel relation with the input capacitance of the circuit to increase the input capacitance for filtering out noise in the circuit to thereby achieve a high signal-to-noise ratio. The bandwidth of the noise signal is kept low to achieve high signal-to-noise ratios and efficient wavelength stabilization. By operating at low bandwidths, the input capacitance of the circuit does not dominate the shunt voltage and associated current due to the noise; rather, a feedback resistance associated with an operational amplifier dominates the magnitude of the noise current.

Abstract: An apparatus controls a light source, which may be a laser. A first detector provides a first electrical signal representing an amplitude of a first light that is output by the light source. A filter receives the first light and provides a filtered light having an amplitude that depends on the amplitude and wavelength of the first light. A second detector provides a second electrical signal representing the amplitude of the filtered light. A switching device, such as a multiplexer, is capable of providing either the first electrical signal or the second electrical signal as its output signal. A common amplifier is coupled to the switching device. The common amplifier amplifies the output signal of the switching device, to alternately provide a first amplified signal and a second amplified signal, representing the first and second electrical signals, respectively.

Abstract: A method and apparatus for stabilizing the wavelength of a laser are disclosed. The invention provides a way to stabilize a laser for applications in dense wavelength division multiplexing (DWDM) systems where frequency spacing is crucial. The invention accomplishes laser stabilization by generating an optical path which is passed through a filter to obtain a signal which is a function of frequency. A second optical path which does not contain a filter is generated to obtain a signal which is a function of power. The signals are then converted from optical to electrical and from analog to digital, and a microcontroller is used to normalize the frequency path with respect to the optical power path, process the signals via software code, and generate a signal which provides feedback to the laser for stabilization.

Abstract: A precision grating period measurement system uses a pair of properly positioned photodetectors to provide sub-Angstrom resolution. That is, the absolute position of a first detector with respect to a zero point in the measurement system is assured by including a second photodetector that measures a retroreflected signal. The system is then “zeroed” on the retroreflected signal such that the subsequent measurements recorded by the first photodetector are a precise measurement of the grating period.

Abstract: A wavelength stabilized laser system includes a laser that produces a laser light. The laser light has an amplitude and a wavelength that vary with the laser temperature. A first detector provides a first signal representing the amplitude of the laser light. A filter has a gain that is a function of the wavelength of the laser light. The filter receives the laser light and outputs a filtered light having an amplitude that varies with the wavelength of the laser light. A second detector provides a second signal representing the amplitude of the filtered light. A transformer has a primary and a secondary. The primary is electrically coupled to the first and second detectors. The primary of the transformer includes a first coil connected to the first detector and a second coil connected to the second detector. The first and second coils of the primary are opposite in polarity from each other.

Abstract: A wavelength stabilized laser system includes a laser that produces a laser light having an amplitude and a wavelength that varies as a function of a temperature of the laser. A temperature control device controls the temperature of the laser. A beam splitter deflects a portion of the laser light. A first detector receives the portion of the laser light from the beam splitter and provides a first signal representing the amplitude of the laser light. A filter has a gain that is a function of the wavelength of the laser light. The filter receives the laser light and outputs a filtered light having an amplitude that varies with the wavelength of the laser light. A second detector provides a second signal representing the amplitude of the filtered light. A sealed housing contains the laser, the first and second detectors and the filter. The housing has a window.

Abstract: An apparatus is provided for cleaving a laser bar into semiconductor chips. The apparatus includes a supporting structure on which a member slides. The apparatus also includes a pair of film layers. The laser bar is positioned between the film layers. A chamber is sealed to the top film layer. The chamber has an inlet through which gas is input. The movement of the member and the downward force caused by the buildup of gas pressure in the chamber induce cleaving of the laser bar at predetermined locations. The laser bar may have score marks at the predetermined locations to produce weak points. Pressure pulses may be coordinated with the movement of the member to break the laser bar at the desired locations.

Abstract: A wavelength-stabilized laser system includes a laser that produces a laser light. The laser light has an amplitude and a wavelength that varies with the temperature of the laser and/or a bias signal provided to the laser. A temperature control device controls the temperature of the laser. A first detector outputs a first signal representing an amplitude of a laser light. A filter receives the laser light and outputs a filtered light having an amplitude that varies with the wavelength of the laser light. A second detector outputs a second signal representing the amplitude of the filtered light. An electromagnetic radiation source transmits electromagnetic radiation through the filter and through a diverging lens. A third detector receives the electromagnetic radiation that passes through the diverging lens. The second detector may be between the diverging lens and the third detector. The third detector outputs a third signal representing an amplitude of the electromagnetic radiation.

Abstract: A method for temperature compensating an optical filter utilizes information relating to the temperature coefficient/constant of the optical filter to identify a value for the feedback resistor in a transimpedance preamplifier contained in a laser control system. Changes or effects in transmission resulting from temperature changes in the optical filter can be compensated by selecting a feedback resistor or resistors having a temperature dependence value and corresponding sign and magnitude to offset the undesirable effects on the transmission resulting from temperature tuning of a laser and thereby varying the temperature dependencies of the optical filter in the signal path.

Abstract: A control system for stabilizing the frequency of optical light output from a laser source including an oscillator for producing a modulation signal and a detection signal. An optical modulator receives the optical light output from the laser source and also receives the modulation signal and outputs a first and second modulator output signal. At least one filter is included for receiving the first modulator output signal and outputting a filtered signal having an amplitude that is a function of the change in frequency of the output light output from the laser source. A first optical detector receives the filtered signal and outputs a first electrical signal. A second optical detector receives the second modulator output signal and outputs a second electrical signal. A wavelength control circuit receives the first and the second electrical signals and the detection signal and outputs a control signal received by the laser source for adjusting the frequency of the optical light.

Abstract: An apparatus and a method for non-contact cleaving a brittle, non-metallic solid material, such as semiconductor material, glass, quartz, ceramic or like material. A pulsating gas jet directs a jet of gas toward a support structure formed of a non-compliant material. The semiconductor material is positioned on the support structure between a pair of film layers. The semiconductor material is scored in at least one location on the material. A plastic buffer material is adhered to the support structure. The semiconductor material and the film layers are moved along the support structure until the score line is at a ledge of the support structure and underneath the source of gas. The jet of gas applies a sufficient force to cleave the semiconductor material as it passes off the ledge of the support structure, while minimizing vibration and/or turbulence. The buffer provides cushioning and inhibits the formation of fractures during the cleaving process.

Abstract: The invention disclosed is a method and apparatus for cleaving semiconductor material without physical contact. Tick marks are formed in a major surface of the material where cleaving is desired. A fulcrum member is moved with respect to the material until a tick mark is in alignment with the fulcrum member. A gas jet, also aligned with the fulcrum member, is applied to the surface of the material to form the cleave.

Abstract: The invention is a method for handling material which may be in the form of semiconductor wafers, bars, and/or chips. The material is mounted to a flexible film which is heated so as to result in an adhesion strength sufficient to hold the material in place, but low enough so that the material can be removed easily when desired.

Abstract: A vacuum collet for handling semiconductor piece parts is formed to include a plurality of separate vacuum ports, disposed in proximity to one another. By selectively turning the vacuum ports "on" and "off", with only one vacuum port turned "on" at a time, a semiconductor chip may be articulated through various 90.degree. rotations to provide the orientation required for placement of the semiconductor chip on a final assembly.