摘要:
The invention provides a remote control device of an acousto-optic tunable filter, which comprises an acousto-optic tunable filter interpolated in an optical transmission line, capable of controlling an output state of an input light signal by being supplied with a surface acoustic wave control signal through a control port; a surface acoustic wave control signal source to generate the surface acoustic wave control signal, which is provided at a remote place from the acousto-optic tunable filter; and a control unit that receives an information of the surface acoustic wave control signal from the surface acoustic wave control signal source through remote transmission means, and supplies the surface acoustic wave control signal to the control port of the acousto-optic tunable filter. According to this invention, the scale of the device using the acousto-optic tunable filter becomes enlarged, the power consumption is increased; and the man power required for the maintenance of the devices can be reduced, and the remote control of the acousto-optic tunable filter can be achieved.
摘要:
The present invention aims at providing optical multiplexing/demultiplexing apparatus and method, in which an optical power balance of each wavelength light of a wavelength division multiplexed signal light at input and output ports thereof can be maintained. Thus, an optical multiplexing/demultiplexing apparatus of the present invention has a basic constitution consisting of: an OADM circuit for branching a signal light of a specific wavelength from a wavelength-division-multiplexed signal light sent from a main optical fiber, and for inserting a signal light of a specific wavelength into the wavelength-division-multiplexed signal light sent from a main optical fiber; and an add-light power control portion for controlling the optical power of add light added in the OADM circuit based on a drop light branched in the OADM circuit. In the add-light power control portion, the optical power of each of drop light and add light is measured to perform a control operation of controlling the ratio between the optical power of the drop light and the optical power of the add light to be constant. Consequently, the optical power of signal light of each wavelength at input and output ports of the optical multiplexing/demultiplexing apparatus can be maintained at a constant level.
摘要:
A gain equalizer which equalizes gain versus wavelength characteristics of an optical amplifier. The gain versus wavelength characteristics of the optical amplifier include first, second and third gain peaks in a wavelength band with the second gain peak being between the first and third gain peaks. The optical amplifier amplifies an input signal in accordance with the gain versus wavelength characteristics to produce an output signal. The gain equalizer includes first, second and third optical filters having first, second and third transparency characteristics, respectively. The first, second and third transparency characteristics are periodic waveforms having different periods related to the wavelength difference between the first and third gain peaks. The second transparency characteristic is a periodic waveform having a period equal to 1/(2n) of the period of the waveform of the first transparency characteristic. The third transparency characteristic is a periodic waveform having a period equal to ¼ of the period of the waveform of the first transparency characteristic. For example, the first transparency characteristic is a periodic waveform with ¼ period extending between the first and third gain peaks, the second transparency characteristic is a periodic waveform with one period extending between the first and third gain peaks, and the third transparency characteristic is a periodic waveform with two periods extending between the first and third gain peaks.
摘要:
An optical device has an optical switching unit and a variable filter, the optical switching unit connects a pair of single direction optical transmission lines to a bi-directional optical transmission line carrying optical signals of different wavelengths in different directions relative to the optical switching unit. The single direction optical transmission lines carry optical signals in single different directions relative to the optical switching unit. The variable filter has first and second opposing terminal pairs such that optical signals of different wavelengths input to one terminal of one terminal pair are filtered with a portion of the different wavelengths being output to one terminal of the opposing terminal pair and the remainder of the different wavelengths being output to the other terminal of the opposing terminal pair. The bi-directional optical transmission line is coupled to one terminal of the variable filter. The optical switching unit may include an optical circulator. The variable filter may be an acousto-optic tunable filter. The optical device have a pair of optical switching units respectively connecting two pairs of single direction optical transmission lines to two opposing terminals of the variable filter through two bi-directional optical transmission lines.
摘要:
An apparatus and method for controlling power levels of individual signal lights of a wavelength division multiplexed (WDM) signal light. The apparatus includes an optical fiber, a coupler and a controller. The WDM signal light travels through the optical fiber. The WDM signal light includes a plurality of individual signal lights which each have a corresponding power level. The coupler decouples a portion of the WDM signal light from the optical fiber. The controller determines the spectrum of the WDM signal light from the decoupled portion and controls the power levels of the plurality of individual signal lights in accordance with the determined spectrum. More specifically, the controller can control the relative power levels of the plurality of individual signal lights with respect to each other. In addition, the controller can control the power levels of the plurality of individual signal lights to perform preemphasis on the WDM signal light. The controller can control the power levels of the plurality of individual signal lights to obtain substantially equal signal to noise ratios of the plurality of individual signal lights as received by a receiver through the optical fiber. The method includes the steps of (a) decoupling a portion of a WDM signal light travelling through an optical fiber (b) determining the spectrum of the WDM signal light from the decoupled portion, and (c) controlling the power levels of individual signal lights of the WDM signal light in accordance with the determined spectrum.
摘要:
A wavelength division multiplex optical amplification transmission system has a broad signal wavelength band and can be easily constructed. A transmission line provided between a lightwave transmitting terminal station and a lightwave receiving terminal station is constructed of optical amplifiers, optical filters and a transmission line. Structuring the transmission line involves the use of an optical amplifier utilizing high-concentration Al added EDFA, thereby proving a module excluding the optical filters with a gain wavelength characteristic in which a gain peak exists within a target wavelength range that should be a signal wavelength band, and there is an ill-balanced symmetry with respect to the gain peak in the target wavelength range. Used is the optical filter given a loss wavelength characteristic in which a loss maximum wavelength with a maximum loss exists in the target wavelength range, a gain simply decreases as a distance from the loss maximum wavelength increases within the target wavelength range, and a characteristic obtained by adding the loss wavelength characteristics is relatively coincident in values with the gain wavelength characteristic.
摘要:
The present invention aims at providing an active optical fiber and an optical fiber amplifier, in which a conversion efficiency of pumping light to be input into the active optical fiber is increased to thereby improve optical amplification characteristic. To this end, the active optical fiber of the present invention is formed with fiber gratings arranged over a predetermined region along the longitudinal direction within the optical fiber doped with a rare earth element, and transmitting signal light and reflecting pumping light. Further, the optical fiber amplifier of the present invention is constituted to comprise a pumping light source for generating pumping light, and a multiplexer for multiplexing signal light and the pumping light to thereby output them into one end of the active optical fiber. Thus, the pumping light is reflected by the fiber gratings so as to go and return within the active optical fiber, thereby improving the conversion efficiency of the pumping light.
摘要:
A communication system including: a transmission apparatus configured to modulate a first light by using a first signal to be transferred and a second signal having a frequency different from a frequency of the first signal so as to generate a first optical signal, modulate a second light by using a third signal to be transferred and a fourth signal having a frequency different from a frequency of the third signal so as to generate a second optical signal, polarization-multiplex the first optical signal and the second optical signal, and transmit a polarization-multiplexed optical signal in which the first optical signal and the second optical signal are polarization-multiplexed, each of the first light and the second light being polarized; and a measuring apparatus configured to measure powers of the second signal and the fourth signal which are included in the polarization-multiplexed optical signal transmitted from the transmission apparatus.
摘要:
An optical adding and dropping device includes a drop section including an input port and having a through port and a plurality of drop ports set as output ports, a first multiplexer adapted to multiplex light from the through port and light from a plurality of add ports, and a spectrum foot removing section provided on the input side of the first multiplexer and adapted to remove a foot of a spectrum of light to be inputted from the add ports to the first multiplexer. The optical adding and dropping device can be configured at a low cost while it has adding and dropping functions.
摘要:
An optical add/drop multiplexer includes a first optical coupler receiving an optical signal including a plurality of multiplexed wavelengths, a wavelength blocker receiving the optical signal from the first optical coupler, and blocking at least one wavelength of the plurality of multiplexed wavelengths, a first wavelength selective switch, having one input port receiving the outputted optical signal from the first optical coupler and a plurality of output ports, demultiplexing a plurality of arbitrarily selected multiplexed wavelengths from the received optical signal, a second wavelength selective switch, having a plurality of input ports, each input port receiving a different optical signal and one output port, multiplexing a plurality of arbitrarily selected wavelength signals on the plurality of input ports, and a second optical coupler receiving the optical signal output from the wavelength blocker and multiplexed wavelength signal from the second wavelength selective switch.