Abstract:
Methods for receiving a signal and a detection circuit are disclosed. The detection circuit and related methods may be useful for the fast and accurate receiving of data signals. The detection circuit generally comprises a first circuit having a first time constant, a second circuit having (i) a common input with the first circuit and (ii) a second time constant, the second time constant being less than the first time constant, and a switch configured to (i) charge the first circuit with an input signal when the switch is in a first state, and (ii) charge or discharge the second circuit with the input signal when the switch is in a second state, the switch having the second state when the input signal is no longer received at the common input.
Abstract:
Devices and methods for effecting and managing the bi-directional transmission of data and communications over a single optic fiber are provided. Methods and devices of the invention utilize fiber-optic transmitters and receivers made for WDM transmission, and at least two slightly different wavelengths, in the 1.5 um range. Devices and methods of the invention facilitate simultaneous bi-directional optical transmission over a long distance, while reducing or eliminating cross-talk.
Abstract:
In a coarse wavelength division multiplexing (CWDM) optical transmission system, a distributed feedback (DFB) laser is tuned so that the peak reflection of the grating overlaps with the gain range of the DFB laser. The diffraction grating is tuned so that the peak is positioned on the long wavelength end of the gain spectrum at a selected temperature. The optical transmission system operates in an environment having a wide temperature range (i.e., about −40° C. to about 85° C.). Heat is applied to the laser and as the laser temperature increases, the gain range overtakes the grating peak. When the gain range and the grating peak overlap at increased laser temperature, laser output is improved.
Abstract:
A method and apparatus is presented for providing improved responsiveness of a receiver device. One embodiment includes a receiver device including an avalanche photodiode (APD), a transimpedance amplifier (TIA), and an automatic gain control (AGC) device configured to adjust the reverse bias voltage applied to the APD according to an approximate DC average of the incoming optical signal. A switch in the AGC device may be used to increase or decrease the time constant of an RC combination determining the DC averaging time period, thereby tailoring the response of the AGC device to characteristics of the incoming data pattern. The resulting receiver exhibits improved responsiveness and sensitivity by adapting to varying data patterns including those with data bursts interspersed with gaps.
Abstract:
A multi-channel optical transmitter generally includes a first light source configured to emit light of a first wavelength, a second light source configured to emit light of a second wavelength, a first modulator configured to modulate the light of the first wavelength, and a second modulator configured to modulate the light of the second wavelength. The first modulator has a first anode and a first cathode, and the second modulator has a second anode and a second cathode electrically isolated from the first anode and the first cathode. The modulators (and optionally the light sources) are on a common substrate. A method of transmitting optical signals generally includes modulating light emitted from a first light source using a first modulator, and modulating light emitted from a second light source using a second modulator, where the first modulator receives a first modulation signal, and the second modulator receives a second modulation signal electrically isolated from the first modulation signal.
Abstract:
A modulated laser system generally includes a light emission region, a modulation region having a plurality of semiconductive layers, at least one of which includes a quantum well layer having a variable energy bandgap, and an isolation region separating the light emission region and the modulation region. The laser may be an electro-absorption modulated laser, the light emission region may include a distributed feedback laser, and the modulation region may include an electro-absorption modulator. The laser may be manufactured by forming a lower semiconductive buffer layer on a substrate, an active layer including one or more quantum well layers having the variable energy bandgap on or above the lower semiconductive buffer layer, an upper semiconductive buffer layer on or above the active layer, a contact layer on or above the upper semiconductive buffer layer, and an isolation region separating the light emission region and the modulation region.
Abstract:
A multi-channel optical transmitter generally includes a first light source configured to emit light of a first wavelength, a second light source configured to emit light of a second wavelength, a first modulator configured to modulate the light of the first wavelength, and a second modulator configured to modulate the light of the second wavelength. The first modulator has a first anode and a first cathode, and the second modulator has a second anode and a second cathode electrically isolated from the first anode and the first cathode. The modulators (and optionally the light sources) are on a common substrate. A method of transmitting optical signals generally includes modulating light emitted from a first light source using a first modulator, and modulating light emitted from a second light source using a second modulator, where the first modulator receives a first modulation signal, and the second modulator receives a second modulation signal electrically isolated from the first modulation signal.
Abstract:
A light-emitting device, multi-channel light-emitting device, and method(s) of making the same are disclosed. The light-emitting device can include a substrate; a lower contact layer on or over the substrate comprising a first lower contact in a first region and a plurality of second lower contacts in a second region; a plurality of light-emitting thin film devices on or over the first lower contact in the first region; a plurality of light-modulating thin film devices on or over the plurality of second lower contacts in the second region; a plurality of first upper contacts on or over the plurality of light-emitting thin film devices; a plurality of second upper contacts on or over the plurality of light-modulating thin film devices; and an isolation region between the first and second regions, electrically separating the plurality of first upper contacts and the plurality of second upper contacts.
Abstract:
The present disclosure provides an optical fiber free space isolator. The optical fiber free space isolator can be used with various laser devices, and includes a magnetic support and an optical subassembly. The magnetic support is mounted at the output port of a laser device, and the optical subassembly is fixed to the magnetic support. The optical subassembly may be housed in a U-shaped slot formed in the magnetic support. The present invention further includes an assembly method for the optical fiber free space isolator.
Abstract:
An apparatus for performing volume measurement of a person, animal or object, and methods of making and using the same are described. The apparatus includes first and second chambers in gaseous communication, first and second pressure sensors that measure the air pressure inside the first and second chambers, a pump configured to move air from or to the first and/or second chambers, and a control system connected to the first and second pressure sensors and the pump. The first and second chambers have a volume that is substantially constant when the internal pressure changes. The control system stores values from the first and second pressure sensors, controls air movement to and/or from the first and second chambers, blocks air transfer between the first and second chambers, and determines the volume of the person, animal or object from pressure measurements before and after an air transfer between the first and second chambers.