摘要:
An inline repeater that uses a forward-pumped DRA that can use a pumping light source such as an FBG pumping light source and a fiber laser, which are the most commonly used, and an optical fiber communication system are realized. The optical fiber communication system comprises silica fiber as a gain medium for Raman amplification to amplify a signal light; a pumping light source that emits a pumping light that co-propagates through the silica fiber in the same direction as the signal light; and a multiplexer disposed between the silica fiber and the pumping light source that multiplexes the signal light and the pumping light, with the multiplexer being provided with a means to multiplex the signal light input thereto having a wavelength longer than the zero-dispersion wavelength of the silica fiber and the pumping light emitted from the pumping light source, and the pumping light source being equipped with a means to emit pumping light, with the longest wavelength of the pumping light being shorter than the shortest wavelength of the signal light by a frequency difference on the low-frequency side of 13.7 to 30 THz.
摘要:
An inline repeater that uses a forward-pumped DRA that can use a pumping light source such as an FBG pumping light source and a fiber laser, which are the most commonly used, and an optical fiber communication system are realized. The optical fiber communication system comprises silica fiber as a gain medium for Raman amplification to amplify a signal light; a pumping light source that emits a pumping light that co-propagates through the silica fiber in the same direction as the signal light; and a multiplexer disposed between the silica fiber and the pumping light source that multiplexes the signal light and the pumping light, with the multiplexer being provided with a means to multiplex the signal light input thereto having a wavelength longer than the zero-dispersion wavelength of the silica fiber and the pumping light emitted from the pumping light source, and the pumping light source being equipped with a means to emit pumping light, with the longest wavelength of the pumping light being shorter than the shortest wavelength of the signal light by a frequency difference on the low-frequency side of 13.7 to 30 THz.
摘要:
An optical fiber communication system is provided which uses remote pumping that is capable of improving pumping efficiency and reducing a noise figure. A coupler (20) of a linear repeater (18) couples signal light to pumping light outputted from a pumping light source (19). The outputted signal light and pumping light reach a linear repeater (25) through transmission fibers (22 to 24) and remote pumping modules (27F and 27R). A coupler (30) of the linear repeater (25) couples the signal light to the pumping light supplied from a pumping light source (29), to output the signal light and the pumping light to the transmission fiber (24). The remote pumping module (27F) divides the pumping light propagated in the transmission fiber (22), from the signal light. The remote pumping module 27F branches the divided pumping light in two directions with a predetermined ratio. After branching, each of the branched pumping light is coupled to the signal light to be supplied to both ends of an erbium-doped fiber. The remote pumping module (27R) is similar in structure to the remote pumping module (27F).
摘要:
An optical fiber communication system is provided which uses remote pumping that is capable of improving pumping efficiency and reducing a noise figure. A coupler (20) of a linear repeater (18) couples signal light to pumping light outputted from a pumping light source (19). The outputted signal light and pumping light reach a linear repeater (25) through transmission fibers (22 to 24) and remote pumping modules (27F and 27R). A coupler (30) of the linear repeater (25) couples the signal light to the pumping light supplied from a pumping light source (29), to output the signal light and the pumping light to the transmission fiber (24). The remote pumping module (27F) divides the pumping light propagated in the transmission fiber (22), from the signal light. The remote pumping module 27F branches the divided pumping light in two directions with a predetermined ratio. After branching, each of the branched pumping light is coupled to the signal light to be supplied to both ends of an erbium-doped fiber. The remote pumping module (27R) is similar in structure to the remote pumping module (27F).
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.
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:
A receiver device receives a signal inputted to one or a plurality of ports as a plurality of received signals, and includes: a phase offset estimating unit that, on the basis of a unique word of each signal block contained in said received signal, estimates the phase offset, and a phase offset compensating unit that, on the basis of a phase offset estimated by said phase offset estimating unit, compensates the phase offset; the receiver device uses a known signal component (unique word) contained in a frequency-domain equalized signal to compensate the phase offset, whereby it compensates complex phase offset fluctuation, and estimates the phase offset of a signal obtained at each port.
摘要:
A polarization state of a transmission signal can be changed at a high speed based on a symbol-rate By switching a first switch, a second switch, and a third switch with time, one of an X-polarized wave_I-signal as a Y-polarized wave_I-signal, a signal caused by performing logical inversion for an X-polarized wave_I-signal, an X-polarized wave_Q-signal and a signal caused by logical inversion for an X-polarized wave_Q-signal is input to a second modulator. Further, by switching the first switch, the second switch and the third switch with time, the second modulator is input one of the X-polarized wave_I-signal as the Y-polarized wave_Q-signal, the X-polarized wave_I-signal, the signal caused by performing logical inversion for the X-polarized wave_I-signal, the X-polarized wave_Q-signal and the signal caused by performing logical inversion for the X-polarized wave_Q-signal. Thereby, a polarization state of a transmission signal can be changed at high speed based on a symbol-rate speed.
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:
A high-performance optical OFDM receiver is realized. A subcarrier separation circuit receives an optical OFDM signal consisting of two subcarriers A and B and separates a subcarrier component, signal light and first local oscillator light are input to the subcarrier separation circuit, the subcarrier separation circuit converts the signal light and the first local oscillator into a baseband electrical signal, the subcarrier separation circuit converts the baseband electrical signal into a digital signal, the subcarrier separation circuit shifts the frequency of the converted digital signal so that a center frequency of the subcarrier A becomes zero, and the subcarrier separation circuit adds a frequency shifted signal to a signal obtained by delaying the frequency shifted signal by ½ of a symbol time to separate a component of the subcarrier A.