Broadband Royalty Corporation

Koninklijke Philips Corporation N.V.

Philips Electronics North America Corporation

Venkatesh G Mutalik

Marcel F Schemmann

Marcel F C Schemmann

A cable television (CATV) distribution system, and a method of forming and using the CATV distribution system. In a first embodiment, a narrowcast optical signal is generated by an uncooled laser and converted by a receiver into a narrowcast electrical signal. In a second embodiment, a narrowcast optical signal generated by an uncooled laser is combined with a broadcast optical signal by an optical coupler at a hub of the CATV distribution system to generate a composite optical signal, which at a CATV node is: split into the broadcast and narrowcast optical components, respectively converted into broadcast and narrowcast electrical components, and combined into a composite electrical signal. In a third embodiment, a narrowcast optical signal is generated by an uncooled laser and then combined with the broadcast optical signal by a single receiver.

Uncooled laser generation of narrowcast CATV signal

A laser transmitter bias circuit for a laser diode transmitter, for use in a optical transmission system, e.g. in commercial CATV systems. The laser transmitter bias circuit reduces power consumption and heat dissipation by eliminating the conventional need for a distinct constant DC current supply for biasing the laser diode. Radio frequency (RF) circuitry, e.g., a radio frequency amplifier (e.g., a Hybrid Amplifier), connected in series to the laser diode supplies both a DC bias-current (I ) and an RF drive-current (I ) through the laser diode. The DC bias current through the laser diode in turn powers (and/or biases) the radio frequency amplifier and, optionally, other radio frequency circuitry. An optional diode-bypass current (I ) path may be connected in parallel with the laser diode, and in series with the radio frequency amplifier to control bias current.

Laser transmitter bias circuit

An in-line pre-compensation circuit distorts an electronic information signal prior to using the signal to modulate a laser beam in order to compensate for distortions resulting from transmitting the resulting optical signal through an optical fiber. The pre-compensation circuit is dynamically adjustable for different lengths of optical fiber for simple installation and maintenance of the system. The adjustment can be made from a front panel of a laser transmitter during operation. Even though the optical signal is more distorted at the output of the laser transmitter, the optical signal that arrives at the receiver is less distorted.

Optical communication with predistortion to compensate for odd order distortion in modulation and travel

An in-line pre-shaper for a laser transmitter distorts an electronic information signal to compensate for distortions resulting from the optical information signal provided by the laser transmitter, being transmitted through an optical cable, as well as, compensating for distortions resulting from using the electronic information signal to modulate the laser beam produced by the laser transmitter to provide the optical information signal. The pre-compensation reduces both second order and third order distortion of the optical signal for the combination of the laser and the optical cable. Even though the optical signal is more distorted at the output of the laser transmitter, the optical signal that arrives at the receiver is less distorted.

Pre-shaping laser modulation signals to increase modulation index

Optical communication with pre-compensation for odd order distortion in modulation and transmission

A method and apparatus for controlling and stabilizing laser wavelengths in a dense wavelength division multiplexer (DWDM) transmission system. The lasers in the transmission system are each modulated in a known manner by a data signal. In addition, the lasers are each modulated by a plurality of test signals each having a predetermined frequency. At the optical receiver, a frequency analyzer examiners the frequency test signals for distortions and/or changes in amplitude. Any distortions and/or changes in amplitude of the frequency test signals indicate a change in the wavelength of a corresponding laser. A control signal may be returned to the laser controller of each laser to regulate the laser wavelength. A fault signal may be generated indicating that the wavelength of a laser has changed, drifted, etc., more an acceptable amount.

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Manlius, NY, United States of America

Venkatesh G Mutalik