Granted: July 1, 2014
Feed-forward and feedback strategies are used to control local oscillator power and transimpedance amplifier gain in a high-speed coherent optical receiver.
Granted: March 18, 2014
A green laser is made by constructing a laser cavity that includes within it a laser diode, a non-linear crystal such as KTP, and a lens. The boundaries of the cavity are not defined by the ends of the diode itself, but are instead defined by the ends of an apparatus that includes the lens and the KTP or similar crystal.
Granted: February 4, 2014
I/Q data skew in a QPSK modulator may be detected by sending identical or complementary data streams to I and Q channel PSK modulators, setting the relative carrier phase between I and Q to zero or ?, and monitoring the average QPSK output power, where the data streams sent to the I and Q channels include streams of alternating ones and zeroes.
Granted: January 21, 2014
Digital timing error detection systems and techniques are described. The described techniques are independent of polarization and differential-group-delay and are used to perform timing recovery of polarization-multiplexed coherent optical systems.
Granted: October 22, 2013
Patterns detected by a low-speed receiver at the output of a high-speed multiplexer are used to determine when multiplexer input lanes are deskewed.
Granted: October 22, 2013
A method for detecting and measuring time skew in high-speed DP-QPSK coherent optical receivers is described.
Granted: September 10, 2013
An adaptive-equalizer initialization system performs three functions: frequency offset estimation, taps estimation for chromatic dispersion filters, and taps initialization for an adaptive equalizer. The system contains hardware FFT and peak detector units that sense a pure tone that marks the beginning of a known, short data sequence.
Granted: May 7, 2013
Systems and techniques for optical communications based on polarization division multiplexing are described.
Granted: April 23, 2013
I/Q data skew in a QPSK modulator may be detected by sending identical or complementary data streams to I and Q channel PSK modulators, setting the relative carrier phase between I and Q to zero or ?, and monitoring the average QPSK output power, where the data streams sent to the I and Q channels include pseudorandom streams of ones and zeroes.
Granted: November 20, 2012
An optical transceiver has a projection covering member that can suppress EMI noise radiated from a pig-tail part. An elastic covering member covers a projection which includes an optical coupler of an optical sub assembly. The covering member is made of a conductive elastic material having a predetermined resistivity. At least a part of an outer circumference surface of the elastic covering member comes into intimate contact with an outer periphery of a conductive opening part of a case…
Granted: September 25, 2012
To detect a wavelength drift of laser light with no error, an optical transmission module (10) includes: a laser diode (20); a laser temperature calculation section (52) for detecting the temperature of the laser diode (20) that monotonously increases with respect to a wavelength of the laser light; a wavelength calculation section (44) for detecting a transmittance of the laser light incident on an etalon filter (36) whose transmittance periodically varies with respect to the wavelength…
Granted: August 14, 2012
Apparatus and methods for receiving and processing optical signals carrying symbols that represent data, including an optical receiver having fractional sampling analog-to-digital conversion and interpolation timing recovery synchronization for processing an optical signal.
Granted: July 10, 2012
Provided are an optical transmitter device and an optical transmitter module which are capable of reducing the optical transmitter module size while maintaining a state where an excellent optical transmission waveform quality is obtained over a wide range of frequencies. The optical transmission module (2) includes a semiconductor laser diode device (10), an optical modulator device (12), and a first termination resistor circuit (14-1). A printed circuit board (4) includes a driver IC…
Granted: July 3, 2012
Disclosed is an optical transmission module in which effects of conductive heat from sides of a metal case upon a thermistor are reduced, thereby allowing steady optical beam wavelengths to be obtained over a wide range of temperatures, regardless of the temperature of the usage environment. Specifically, the optical transmission module includes Peltier elements disposed inside a metal case, a metal base disposed upon the Peltier elements, a laser diode substrate disposed upon the metal…
Granted: June 19, 2012
Provided is an optical module including: an optical assembly incorporating a light emitting or receiving device for converting one of an electrical signal and an optical signal into another of the electrical signal and the optical signal; a circuit board electrically connected to the optical assembly; an optical fiber optically connected to the optical assembly; a tray for winding the optical fiber therein and pulling out the optical fiber therefrom; and a case receiving the optical…
Granted: May 15, 2012
A wavelength tunable filter and a wavelength tunable laser module are a codirectional coupler type whose characteristics do not vary significantly with a process error. They are structured so as to include a semiconductor substrate which has a first optical waveguide and a second optical waveguide. The first and the second optical waveguides are extended from a first side of the semiconductor substrate to an opposing second side thereof. The first optical waveguide includes a first core…
Granted: March 6, 2012
Provided is an optical transmission circuit capable of realizing a high-quality optical signal waveform with low power consumption. An optical transmission circuit (10) includes: a laser diode (800); a modulator (900) for supplying a differential modulation current to an anode terminal and a cathode terminal of the laser diode (800) through transmission lines (301 to 304); a current source (101) for supplying a forward bias current to the laser diode (800); and a magnetic sheet (wave…
Granted: February 28, 2012
In an InGaN-based nitride semiconductor optical device having a long wavelength (440 nm or more) equal to or more than that of blue, the increase of a wavelength is realized while suppressing In (Indium) segregation and deterioration of crystallinity. In the manufacture of an InGaN-based nitride semiconductor optical device having an InGaN-based quantum well active layer including an InGaN well layer and an InGaN barrier layer, a step of growing the InGaN barrier layer includes: a first…
Granted: February 28, 2012
Optical communication apparatus, methods, systems are provided based on balanced-detection phase-shaped binary transmission (BD-PSBT).
Granted: February 21, 2012
Provided are an optical receptacle capable of manufacturing an optical module thereby, while suppressing a manufacturing cost, preventing a quality degradation, and suppressing a quantity of returning light by reflection. In the optical receptacle, a recess for receiving a lens and a lens support and a through-hole penetrating from a bottom of the recess toward an exterior are formed, and the recess is formed so that an inner peripheral surface of the recess is fixed to a desired…