Lucent Technologies Inc.

At+t Corp.

American Telephone & Telegraph Co., At&t Bell Laboratories

Go!foton Holdings, Inc.

Agere Systems Optoelectronics Guardian Corp.

Other

At&t Bell Laboratories

Agere Systems Guardian Corp.

Go!foton Corporation

Golfoton Holdings, Inc.

Zenko Technologies, Inc.

Ota, Yusuke

Yusuke Ota

Robert G Swartz

Stephen R Forrest

Kenichiro Takeuchi

Eduard Sackinger

Wilhelm C Fischer

Paul A Kohl

Alfred E Dunlop

David Andrew Inglis

Wilhelm Carl Fischer

Michael G Brown

Harvey S Trop

Daniel R Kaplan

Jangsun Kim

Richard A Van Wijk

Theo W Mosch

Jian-Guang Chen

David A Inglis

A digital burst mode communication system operates at a fixed wavelength for transmission and reception of burst mode signals using a pair of transceivers and a single optical cable. The stray noise level in the system is significantly reduced by use of angled plate absorbers that receive scattered transmission burst signal from a 45 degree partially reflecting mirror. Use of transparent glass ferrule with or without a front surface anti-reflection coating instead of an opaque ceramic ferrule to support optical fiber at a selected location within the transreceiver reduces optical detector signal noise. Isolation of received burst signal from transmitted burst signal is increased to better than 30 dB. The system operates by sending only data bits across the single optical cable without scrambling or encoding preambles, significantly improving the efficiency of high speed communication.

Two way burst mode digital optical cable communication system

A digital burst mode communication system operates at a fixed wavelength for transmission and reception of burst mode signals using a pair of transceivers and a single optical cable. The stray noise level in the system is significantly reduced by use of angled plate absorbers that receive scattered transmission burst signal from a 45 degree partially reflecting mirror. Isolation of received burst signal from transmitted burst signal is increased to better than 30 dB. The system operates by sending only data bits across the single optical cable without scrambling or encoding preambles, significantly improving the efficiency of high speed communication.

A passive optical network system and method in which at least part of the data is optically transmitted through a single optical fiber using a wavelength division multiplexing technique, with a plurality of signals being carried through the fiber in each direction, a different wavelength being used for each of the multiplexed upstream and downstream signals. The system may be retrofitted into existing telecommunications system to provide a multi-fold increase in the available bandwidth of long-distance optical fiber transmission.

Optical fiber network with improved fiber utilization

An optical network unit useful in a passive optical network has capability for automatic shutdown upon detection of a malfunction, thereby protecting the integrity of upstream data transmitted in the network. The unit detects the generation of upstream light during intervals in which transmission is not authorized. In response, the light source of the unit is deactivated to prevent collisions with upstream data from other optical network units in the network.

Optical network unit having automatic shutdown

A clock and data recovery circuit and method are used in a digital data communications system. The circuit and method are effectively employed for high speed, burst-mode transmission and allow rapid recovery of the clock and data signals without the need for an extended header, and notwithstanding the presence of substantial timing jitter. The method adaptively selects from among three delay times for the extraction of data by identifying a frequently recurring incoming pattern in the incoming data. The delay time is selected in a manner that insures that the same pattern is present in the reconstructed, resynchronized output data.

Data sampling circuit and method for clock and data recovery

An optical network unit is associated with a multi-wavelength optical fiber communications system carrying low-power digital signals bidirectionally transmitted at a first and a second wavelength and a high-power analog video signal transmitted at a third wavelength. The unit comprises a housing having a connection for the optical fiber; and an optical filter, first and second optical units, and a beam splitter mounted in the housing. The optical filter is interposed between the fiber termination and the second optical unit, and is adapted to block light of the third wavelength but bidirectionally transmit light of the first and second wavelengths. The system is readily implemented, and any combination of the data and video services may be selected. A high level of skill is not required for changing the combination of services procured.

Multi-wavelength, bi-directional optical multiplexer

The clock may be recovered rapidly for burst mode signals that are at one of a set of different a priority known frequencies by using a single device that is similar to that of U.S. Pat. No. 5,237,290 except that the delay lines used in each of the gated oscillators are controllably selectable so that the gated oscillators are each capable of providing a clock signal at more than one frequency. Typically, the same frequency is selected for use by both of the gated oscillators at any one time. This is achieved by having each gated oscillator be made up of 1) a plurality of &ldquo;internal&rdquo; gated oscillators that each have different length delay lines, and 2) a selector for selecting the output of one of the internal gated oscillators that is to be used for a particular frequency. The internal gated oscillators may be made up of delay elements. The ratio of the number of delay elements in the various internal gated oscillators to each other determines their relative frequency. When the delay elements that make up the internal gated oscillators are inverters, a phase splitter may be employed to insure that the number of delay elements effectively remains odd to insure that oscillation takes place even when a ratio of two in the frequencies recovered is required.

Clock recovery from a burst-mode digital signal each packet of which may have one of several predefined frequencies

Power control for a laser is performed on at least a per-packet basis, rather than a per-pulse basis, and that end-of-life detection may similarly be performed. This is achieved by accumulating the current generated by a photodiode in response to the light signal generated by the laser, subtracting therefrom a preset threshold current which is similarly modulated in response to the data signal used to drive the laser, and comparing the resulting difference to the value prior to having begun accumulating and subtracting. The result of the comparison, which may be filtered, is used to control the driver of the laser or as an indicator, e.g., for use in end-of-life detection.

Burst-mode lase techniques

Power control for a laser used for bust mode communication as well as end-of-life detection for the laser are performed in a combined manner, resulting in a savings in both cost and power consumption. This is achieved by employing a peak comparator which is supplied with an indication of the magnitude of a the laser signal, and supplying to the peak comparator in a time multiplexed manner with different thresholds, such as a first threshold which is used for performing power control and a second threshold which is used for performing end of life detection, on an alternative packet-by-packet basis. Thus, the first threshold is supplied for the duration of a first packet and the second threshold is used for the duration of a second packet. Additional thresholds and packets may be employed for other functions as desired by an implementor.

Burst-mode laser techniques

A bipolar peak detector that maintains the charge on its capacitor longer than prior art peak detectors can due to the discharging thereof that occurs during long periods of reception of only a single value in the received signal, e.g. a long string of zeros, by substantially exactly duplicating, i.e., duplicating to within manufacturing tolerances, the current that is leaking out of the capacitor and injecting the duplicate current into the capacitor.

Peak detector

A DC coupled burst mode optical receiver circuit having improved sensitivity and improved dynamic range. The output of the receiver's photodiode is single endedly amplified by a main preamplifier and the main preamplifier's output is then converted, using an operational amplifier, e.g., with a gain of 1, to a differential signal which swings symmetrically around a threshold level. More specifically, the output of the main preamplifier is connected to one input of the operational amplifier. The output of a tracking preamplifier, which is identical to the main preamplifier, is coupled to the other input of the operational amplifier. The output of the tracking preamplifier is used to match the DC voltage of the main preamplifier, e.g., by being noise-free and by tracking changes in supply voltage, temperature, and the like. It is used to set the DC reference voltage for the standard operational amplifier functions. Between one output of the operational amplifier and the opposite sign input thereof is connected an automatic threshold controller (ATC). The ATC insures that the threshold level for determining the value of the logic value of the received signal is at the middle of the signal supplied from the main preamplifier. Preferably, the main preamplifier, the tracking preamplifier, the operational amplifier and the ATC are manufactured on a single integrated circuit. Optionally, a transimpedance resistor of both the main preamplifier and the tracking preamplifier are clamped to a predetermined maximum level, e.g., using a high-speed Schottkey diode, to enhance the dynamic range of the receiver.

Burst mode digital optical receiver

The length of the tail which results in an optical output from a laser diode after the laser diode is no longer being driven is reduced or eliminated by a laser diode driver with a tail eliminator. More specifically, the laser diode driver includes an energy drainage path that is activated when packet communication is over. In one embodiment of invention, the terminals of the laser diode are short-circuited to provide the energy drainage path. In another embodiment of the invention, the laser diode is reverse biased, so that charges stored in the laser diode are combined with charges which are provided thereto. Advantageously, the tail emission is substantially eliminated.

High speed non-biased semiconductor laser dione driver for high speed

A digital burst-mode packet data receiver receives high-speed burst-mode packet data signals superimposed on a lower frequency data signal. The receiver includes a first detector for detecting the received high-speed burst-mode packet data which is reset during the time period between consecutive bursts of the high-speed packet data signal. A second detector detects the lower frequency data signal during a predetermined portion of the time period between consecutive bursts of the high-speed packet data.

Packet data reciever with sampled data output and background light

A dc-coupled packet mode digital data receiver, for use with an optical bus uses peak detectors to adaptively establish an instantaneous logic threshold at the beginning of a data burst. A dc compensator, responsive to outputs of the peak detectors, shunts dc or low frequency currents, corresponding to 'dark level' optical signals, from the input of the receiver.

Growing community of inventors

Mountain Lakes, NJ, United States of America

Yusuke Ota