Hewlett-packard Company

Hewlett-packard Corporation

Christian Hentschel

Wolfgang Schmid

Emmerich Mueller

Edgar Leckel

Clemens Rueck

Dietmar Patz

Described is a noise figure measurement for optical amplifiers by disabling a signal of a channel before the measurement of the amplified spontaneous emission for that channel and by distributing a power equivalent which is substantially equal to the power of the signal of the disabled channel, at at least one other wavelength. The noise figure measurement can be used as well in multi-channel applications such as WDM, as in a single channel operation.

Noise figure measurement of optical amplifiers by power substitution

A method and apparatus for measuring the noise level in an optical amplifier in the presence of a signal at a signal wavelength. The signal is detuned to a second wavelength different from the signal wavelength. A difference function corresponding to the difference in noise levels before and after detuning of the signal as a function of wavelength is determined. The noise level at the signal wavelength is measured. The value of the difference function at the signal wavelength is added to the noise level measured in the previous step.

Method of measuring the noise level in the presence of a signal

This invention relates to a method and an apparatus for the measurement of amplified spontaneous emission (ASE) noise of an erbium-doped fiber amplifier in the presence of an optical signal. The known technique to perform ASE measurement at the actual signal wave length is called pulse-recovery technique. The disclosed technique requires two highly blocking optical switches for the incident and the outgoing laser beams of the amplifier having a short switching time and switching both beams synchronously with high accuracy. An inventive method comprises a first step in which a first optical signal is supplied to said optical circuit via means for blocking and in which second optical signal, generated by said optical circuit, is supplied to at least one means for analyzing said second signal via said means for blocking and a second step in which said first optical signal is blocked by said means for blocking and in which said second optical signal is still supplied to said means for analyzing said second signal via said means for blocking.

Method and apparatus for analyzing the characteristics of an optical

A protective circuit for a semiconductor laser supplied with an excitation current by a current generator circuit is created using a transducer, whose output is controlled by the laser light, a limit circuit cooperating with the transducer and a current shunt circuit energized by the limit circuit and switched in parallel with the semiconductor laser. Once the permissible emitted light power is reached, excessive excitation current is diverted to the shunt circuit. Exemplary embodiments of the invention are found to achieve response times below 20 ns and are able to protect the semiconductor laser from overload currents even during power-on and power off.

Protective circuit for a semiconductor laser

A circuit for the conversion of an electrical input signal into an optical output signal is disclosed. A portion of the main beam from a laser diode that provides the optical output is reflected to a PIN diode with a glass pane. Linearization of the electro-optical conversion process over a wide frequency range is achieved through a feedback loop. For operation at frequencies higher than that of the feedback loop bandwidth, the various conversion factors for low and high frequencies can be additionally adapted.

Electro-optic circuit with source control feedback

A safety device for a light signal generator only activates a laser beam emerging from an optical fiber connector when an optical fiber is connected. By inserting a plug of the optical fiber into the connector of the light signal generator a photodetecting circuit is caused to provide a control signal, which activates the laser.

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Gaufelden, Germany

Christian Hentschel