Burst optical communication apparatus

• US 20050249506A1
• Filed: 06/29/2005
• Published: 11/10/2005
• Est. Priority Date: 10/29/1999
• Status: Active Grant

• Current Assignee: Masaru Fuse
• Original Assignee: Masaru Fuse
• Inventors: Fuse, Masaru
• Granted Patent: US 7,151,896 B2
• Time in Patent Office: Days
• US Class Current: 398/183
• CPC Class Codes: H04B 10/505 using external modulation
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

First and second carrier modulators each modulate a carrier having a different frequency from each other with a baseband input signal. First and second variable wavelength optical modulators each convert the modulated signal into an optical signal having a first or second wavelength. An optical multiplexer multiplexes the optical signals, and sends a multiplexed signal to an optical transmission line. A wavelength separator individually outputs wavelength components of the multiplexed signal. First and second optical receivers each convert these wavelength components into an electrical signal. First and second filters each pass only the signal components of each different frequency. First and second burst demodulators each demodulate the modulated signal. With such a structure, a large-capacity optical communication apparatus which is capable of simultaneously using the same wavelength without requiring wavelength management in optical transmitting circuits can be achieved at a low cost.

Claims

1. An optical communication apparatus for transmitting an intermittent optical signal from a transmitting side to a receiving side by using wavelength information of the optical signal as an address, said optical communication apparatus comprising:

at least two optical transmitting circuits operable to send the intermittent optical signal;

at least two optical receiving circuits operable to receive the optical signal sent from each of said optical transmitting circuits, said at least two optical receiving circuits each being operable to receive a respective predetermined wavelength of the optical signal sent from each of said optical transmitting circuits; and

an optical transfer circuit having at least two output ports operable to connect each of said optical transmitting circuits to each of said optical receiving circuits;

wherein;

each of said optical transmitting circuits is operable to provide a variable wavelength and intermittently send burst optical signals which are generated by varying the intermittent optical signal so as to prevent a collision among the generated burst optical signals due to a coincidence in wavelength or an overlap between time periods in which the burst optical signals are sent;

said optical transfer circuit is operable to multiplex the burst optical signals outputted from said optical transmitting circuits, to separate the multiplexed burst optical signal into optical signals for each predetermined wavelength corresponding to said optical receiving circuits, and to individually output the separated optical signals from said output ports;

each of said optical receiving circuits is operable to convert the optical signal outputted from a corresponding one of said output ports into an electrical signal, and to intermittently output the electrical signal;

each of said optical transmitting circuits includes

a carrier modulator operable to modulate a carrier having a frequency unique to each of said optical transmitting circuits with the intermittent input signal to generate a burst modulated signal, and to intermittently output the burst modulated signal, and

a variable wavelength optical modulator operable to convert the burst modulated signal from said carrier modulator into a burst optical signal, to set a wavelength thereof to any one of at least two predetermined varying wavelengths corresponding to said optical receiving circuits, and to intermittently send the burst optical signal;

said optical transfer circuit includes

an optical multiplexer operable to multiplex the burst optical signals outputted from said optical transmitting circuits, and to intermittently output a multiplexed optical signal, and

a wavelength separator operable to separate the multiplexed optical signal inputted from said optical multiplexer into optical signals of the predetermined wavelengths corresponding to said optical receiving circuits, and to individually output the separated optical signals from said output ports; and

each of said optical receiving circuits includes

an optical receiver operable to convert the optical signal outputted from the output port corresponding thereto in said wavelength separator into an electrical signal, and to intermittently output the electrical signal,

a filter operable to receive the electrical signal intermittently outputted from said optical receiver, to selectively pass any one of the burst modulated signals from said optical transmitting circuits based on the received electrical signal, and to output the passed burst modulated signal, and

a burst demodulator operable to demodulate the burst modulated signal intermittently outputted from said filter.

2. The optical communication apparatus according to claim 1, further comprising an optical sub-transmitting circuit, wherein:

said optical sub-transmitting circuit includes

a carrier generator operable to multiplex reference carriers that are equal in frequency to and have a predetermined relation in phase with the carriers unique to said optical transmitting circuits, and to output a multiplexed signal, and

an optical sub-modulator operable to convert the multiplexed signal outputted from said carrier generator into an optical signal having a predetermined wavelength that is different from said predetermined varying wavelengths corresponding to said optical receiving circuits, and to send the optical signal;

said optical multiplexer is operable to multiplex the burst optical signals outputted from said optical transmitting circuits and the optical signal outputted from said optical sub-transmitting circuit, and to output a multiplexed optical signal;

said wavelength separator is operable to separate the multiplexed optical signal outputted from said optical multiplexer into optical signals for each of the predetermined wavelengths corresponding to said optical receiving circuits and an optical signal having a wavelength equal to the wavelength of the optical signal sent from said optical sub-modulator, and to individually output the separated optical signals from said output ports and a carrier output port provided thereto;

each of said optical receiving circuits further includes

an optical sub-receiver operable to convert the optical signal outputted from the carrier output port of said wavelength separator into an electrical signal, and to output the electrical signal, and

a sub-filter operable to receive the electrical signal outputted from said optical sub-receiver, to selectively pass any one of said reference carriers based on the received electrical signal, and to output the passed reference carrier; and

said burst demodulator is operable to demodulate the burst modulated signal intermittently outputted from said filter with reference to the reference carrier outputted from said sub-filter.

3. The optical communication apparatus according to claim 2, wherein the burst modulated signal is generated by any one of frequency modulation and phase modulation.

4. The optical communication apparatus according to claim 3, wherein said burst demodulator is operable to carry out synchronous detection of the burst modulated signal intermittently outputted from said filter with reference to the reference carrier outputted from said filter.

5. The optical communication apparatus according to claim 1, wherein:

said carrier modulator is operable to modulate the carrier having the frequency unique to each of said optical transmitting circuits to generate the burst modulated signal and to intermittently output the burst modulated signal and the carrier;

each of said optical transmitting circuits further includes an optical sub-modulator operable to convert the carrier outputted from said carrier modulator into an optical signal having a predetermined wavelength that is different from the predetermined varying wavelengths corresponding to said optical receiving circuits, and to send the optical signal;

said optical multiplexer is operable to multiplex the burst optical signals from variable wavelength optical modulator included in each of said optical transmitting circuits and the optical signal from said optical sub-modulator, and to output a multiplexed optical signal;

said wavelength separator is operable to separate the multiplexed optical signal outputted from said optical multiplexer into optical signals for each of the predetermined wavelengths corresponding to said optical receiving circuits and an optical signal having a wavelength equal to the wavelength of the optical signal sent from said optical sub-modulator, and to individually output the separated optical signals from the output ports and a carrier output port provided thereto;

each of said optical receiving circuits further includes

an optical sub-receiver operable to convert the optical signal outputted from the carrier output port of said wavelength separator into an electrical signal, and to output the electrical signal, and

a sub-filter operable to receive the electrical signal outputted from said optical sub-receiver, to selectively pass any one of said reference carriers based on the received electrical signal, and to output the passed reference carrier; and

said burst demodulator is operable to demodulate the burst modulated signal intermittently outputted from said filter with reference to the reference carrier outputted from said sub-filter.

6. The optical communication apparatus according to claim 5, wherein the burst modulated signal is generated by any one of frequency modulation and phase modulation.

7. The optical communication apparatus according to claim 6, wherein said burst demodulator is operable to carry out synchronous detection of the burst modulated signal intermittently outputted from said filter with reference to the reference carrier outputted from said sub-filter.

8. The optical communication apparatus according to claim 1, wherein each of said optical receiving circuits further includes a monitor operable to monitor the electrical signal outputted from said optical receiver to determine whether the burst modulated signal from each of said optical transmitting circuits is present or not, and, if present, controls said filter to selectively pass a predetermined burst modulated signal for output.

9. The optical communication apparatus according to claim 1, wherein:

said filter and said burst demodulator are provided as many as the optical transmitting circuits in each of said optical receiving circuits; and

each of said filters is operable to selectively pass a different one of the burst modulated signals from said optical transmitting circuits, and to intermittently output the passed burst modulated signal.

10. An optical transmission apparatus for transmitting an optical signal to a plurality of optical receivers by using wavelength information of the optical signal as an address, said optical transmission apparatus comprising:

a carrier modulator operable to modulate carriers with input signals to generate burst modulated signals;

a variable wavelength optical modulator operable to convert the burst modulated signals into burst optical signals, and to set a wavelength thereof to any one of predetermined varying wavelengths corresponding to said optical receivers; and

an optical multiplexer operable to multiplex the burst optical signals to produce the optical signal, and to intermittently output the optical signal.

11. An optical separating apparatus for separating an input burst optical signal into separated optical signals and for outputting the separated optical signals to a plurality of optical receivers by using wavelength information of the optical signal as an address, said optical separating apparatus comprising:

a separator operable to separate the input burst optical signals having a wavelength corresponding to the receiver respectively, into the separated optical signals according to each wavelength; and

an output port operable to output the separated optical signals.