摘要:
An optical transmission system is provided in which the optimum operating point of a Mach-Zehnder interferometer, matched to the optical frequency of the light source on the transmitting side, can be set. The optical receiver (2) has an infinitesimal-modulated signal component detection circuit (222), which uses the signal train output from a balanced detection circuit (221) to detect the infinitesimal-modulated signal component applied to the phase adjustment terminal (201) of an MZI (200) by an infinitesimal-modulated signal oscillation circuit (224); a synchronous detection circuit (223), which synchronously detects the infinitesimal-modulated signals output from the infinitesimal-modulated signal component detection circuit (222) and infinitesimal-modulated signal oscillation circuit (224) and detects the error signal component arising from the shift between the optical signal carrier frequency and the optical frequency characteristic of the MZI (200); and a controller (207), which outputs a control signal to adjust the phase difference between two split optical signals output from the MZI (200) so as to correct the shift amount.
摘要:
An optical transmission system is provided in which the optimum operating point of a Mach-Zehnder interferometer, matched to the optical frequency of the light source on the transmitting side, can be set. The optical receiver (2) has an infinitesimal-modulated signal component detection circuit (222), which uses the signal train output from a balanced detection circuit (221) to detect the infinitesimal-modulated signal component applied to the phase adjustment terminal (201) of an MZI (200) by an infinitesimal-modulated signal oscillation circuit (224); a synchronous detection circuit (223), which synchronously detects the infinitesimal-modulated signals output from the infinitesimal-modulated signal component detection circuit (222) and infinitesimal-modulated signal oscillation circuit (224) and detects the error signal component arising from the shift between the optical signal carrier frequency and the optical frequency characteristic of the MZI (200); and a controller (207), which outputs a control signal to adjust the phase difference between two split optical signals output from the MZI (200) so as to correct the shift amount.
摘要:
An optical transmitter for realizing a high tolerance with respect to the group velocity dispersion of the optical fibers, a small receiver sensitivity degradation, and an improved stability that is hardly affected by the group velocity dispersion even in the case of network scale expansion, is constructed by a light source section for generating optical clock pulses synchronized with a signal bit rate while maintaining a duty ratio of the optical clock pulses constant, which is capable of variably setting the duty ratio, and an encoding section for encoding the optical clock pulses by using electric signals synchronized with the optical clock pulses while setting a relative optical phase difference between the optical clock pulses in adjacent time-slots to be an odd integer multiple of &pgr;.
摘要:
In a transmitter side in an optical transmission system, an input binary signal is converted into a duobinary signal, and the duobinary signal is applied to an optical modulation device which provides an optical intensity modulation signal, wherein the optical intensity for a center value of the duobinary signal is a minimum, the optical intensity for the other two values of the duobinary signal is a maximum, and an optical phase for those two values is opposite to each other. In a receiver side, simple direct detection is carried out for receiving optical signal through an optical transmission line to provide a demodulated binary signal. Thus, an original binary signal is recovered without a duobinary decoder and receiver sensitivity degradation. In the optical transmission system, an optical carrier frequency component in a signal spectrum is suppressed, a signal bandwidth of the modulated light is reduced in half to that of a prior art, so an optical transmission system for long distance, high bit rate and large traffic capacity is obtained.
摘要:
A multi-flow optical transceiver provided with a plurality of wavelength-tunable light sources, a plurality of optical modulation units which modulates light with an input signal, an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, and an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide.
摘要:
A bandwidth variable communication apparatus includes: a route exchange unit including a route exchange function for switching an output port of a stream signal of one or more wavelengths input from an input port based on both or a part of wavelength and time, and including a bandwidth change function for changing passable frequency bandwidth in a section from the input port to the output port through which the stream signal passes; and a control unit including a control information transmit-receive function for transmitting and receiving control information for both or a part of the route exchange function and the bandwidth change function of the route exchange unit, and including a control function for controlling the route exchange unit based on the control information. All or a part of the input ports and the output ports are connected to other communication apparatuses via transmission routes.
摘要:
The present invention relates to an optical receiver, in which the transmittance of a Mach-Zehnder interferometer can be locked at a normal operation point in a simple structure and control. A transmittance detecting circuit and a minute modulation signal detecting circuit are provided in parallel after a balanced optical receiver, and a switch is selectively connectable either a minute modulation signal detecting circuit and a transmittance detecting circuit. In the initial stage of frequency pull-in, the switch is set to connect the transmittance detecting circuit to the synchronous detection circuit. If the transmittance detecting circuit detects that the transmittance of the Mach-Zehnder interferometer at the carrier frequency becomes a desired transmittance, the connection of the switch is switched from the transmittance detecting circuit to the minute modulation signal detecting circuit.
摘要:
An optical transmission system which provides bandwidth restricted optical signal comprises an input terminal (10) for accepting an electrical binary signal, an amplifier (12) for amplifying said electrical binary signal to the level requested for operating an electrical-optical converter (16) such as a Mach Zehnder light modulator, a bandwidth restriction means (14) which is for instance a low pass filter for restricting bandwidth of said electrical binary signal, and an electrical-optical conversion means (16) such as a Mach Zehnder light modulator for converting electrical signal to optical signal. Because of the location of the low pass filter (14) between an output of the amplifier (12) and the Mach Zehnder light modulator (16), the amplifier (12) may operate in saturation region to provide high level output signal enough for operating the Mach Zehnder light modulator, and a signal shaped by the low pass filter (14) is applied to the Mach Zehnder light modulator (16) with excellent waveform. The invention is useful for long distance, large capacity and low cost optical transmission system.
摘要:
An optical transmission system is provided in which the optimum operating point of a Mach-Zehnder interferometer, matched to the optical frequency of the light source on the transmitting side, can be set. The optical receiver (2) has an infinitesimal-modulated signal component detection circuit (222), which uses the signal train output from a balanced detection circuit (221) to detect the infinitesimal-modulated signal component applied to the phase adjustment terminal (201) of an MZI (200) by an infinitesimal-modulated signal oscillation circuit (224); a synchronous detection circuit (223), which synchronously detects the infinitesimal-modulated signals output from the infinitesimal-modulated signal component detection circuit (222) and infinitesimal-modulated signal oscillation circuit (224) and detects the error signal component arising from the shift between the optical signal carrier frequency and the optical frequency characteristic of the MZI (200); and a controller (207), which outputs a control signal to adjust the phase difference between two split optical signals output from the MZI (200) so as to correct the shift amount.
摘要:
A system which improves wavelength tolerance, compensates dispersion in a simple way, reduces limitation of the fiber input power is disclosed. The operation includes receiving a clock signal from a system clock source; modulating a single mode optical signal based on the clock signal and generating an optical pulse signal having two longitudinal modes, the frequency interval thereof being n×B, n being a natural number and B being a transmission speed; generating a partial response signal by converting a binary NRZ signal from a digital signal source in synchronism with the system clock source; and modulating the optical pulse signal based on the partial response signal, and outputting a binary RZ modulated signal. The binary RZ modulated signal is input into a receiver, where two partial response components in the optical spectra of the input signal are divided, and one or both of the components are received.