Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Eckhard Meissner

Franz Auracher

Bernd Noll

Alfred Ebberg

Julius Wittmann

Hermann J Rodler

Hermann-Johann Rodler

Apparatus and method for obtaining a phase insensitive and/or polarization insensitive optical heterodyne reception for a FSK modulated transmission signal which uses a low intermediate frequency relative to the data rate of the transmission signals and at every clock of the transmission signal, the phase is keyed between 0 and 90.degree. at the starting time and in the middle of the clock time the polarization of the signal is keyed between two mutually orthogonal polarization conditions at the start of the second and the start of the fourth quarter of the clock time and the phase independent and/or polarization independent output signal of the receiver is obtained from the signal which is shift keyed in a simple optical heterodyne receiver for FSK modulated transmission signals.

Method and apparatus for obtaining phase in sensitive and/or

Method and apparatus for obtaining phase and/or polarization-insensitive optical heterodyne receiving for DPSK or ASK-modulated transmission signal wherein an intermediate frequency which is very low as compared to the data rate of the signals is utilized and at every clock of the transmission signal the phase of the signal is shift keyed between 0.degree. and 90.degree. at the start A1 and in the middle M of the clock time T and the polarization of the signal is shift keyed at least at the start A2 of the second and at the start A4 of the fourth quarter of the clock time T. The transmission signal which is shift keyed in this manner is received by a simple optical heterodyne receiver which has the special characteristics that an intermediate frequency filter ZFF is an integrator which integrates over a respectively one-quarter of the clock time T.

Method and apparatus for obtaining phase or polarization insensitive

An apparatus for generating an FSK-modulated optical signal has an optical two-filter FSK super-heterodyne receiver. The optical signal has two different polarization conditions that are orthogonal to one another. Due to the two-filter receiver and orthogonal conditions, polarization-independent reception is possible. Conversion of the polarized, optical signal into the optical signal having the orthogonal polarization conditions is accomplished by a switching device. Each condition has a corresponding bit status of a data signal. The data signal effectively controls the polarizatiion of the optical signal. Hence, the frequency boost can be freely selected while maintaining excellent bandwidth characteristics and optimum sensitivity.

Apparatus for generating an FSK-modulated optical signal having two

An external optical resonator for a semiconductor laser is composed of an optical directional coupler which can be formed as an integrated optical coupler with a short structural length that enables a free spectral range in the order of 100 GHz and enables the resonator and the system fiber to be coupled to the same end face of the laser. The resonator structure includes two optical waveguides with feedback means applied on the end faces of one of the waveguides and the other waveguide having one end face coupled to receive the output of the laser and the other end face of the other waveguide being coupled to the system fiber. The arrangement is particularly useful for tunable semiconductor lasers, particularly for heterodyne reception.

External optical resonator for a semiconductor laser

A method for generating an FSK-modulated optical signal with an optical two-filter FSK super-heterodyne receiver. The optical signal has two different polarization conditions that are orthogonal to one another. Due to orthogonal conditions, polarization-independent reception is possible. Synchronized polarization shifting occurs to generate a polarized modulated optical signal having alternating orthogonal polarization conditions. A delay stage for delaying the switching signal by one-half a clock period ensures accurate synchronization. The frequency shift of the FSK-modulated signal can be freely selected while maintaining excellent bandwidth characteristics and optimum sensitivity.

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Munich, Germany

Eckhard Meissner