Signal detection device, signal detection method, and program

1 . A signal detection device comprising:

a mode demultiplexer configured to convert N (N is a natural number) spatial mode signals including a plurality of higher modes excited in a transmission path fiber into N base modes and output the N basis modes;

a frequency conversion unit configured to convert frequencies of respective N optical signals into frequencies different from each other;

a multiplexing unit configured to multiplex the N optical signals having frequencies that have been converted; and

a reception unit configured to photoelectrically convert a multiplexed optical signal while maintaining modulation information for a phase and polarization, perform digital signal conversion and signal processing, and demodulate an original information sequence.

2 . The signal detection device according to claim 1 ,

wherein the reception unit is configured to perform digital signal processing and signal processing after dividing a signal obtained by photoelectrical conversion into parallel signals including a plurality of signal bands.

3 . The signal detection device according to claim 1 ,

wherein the frequency conversion unit is configured to perform the frequency conversion for each piece of polarization after performing polarization processing on input light, and multiplex a signal on which the frequency conversion has been performed.

4 . The signal detection device according to claim 1 ,

wherein the frequency conversion unit is configured to demultiplex a wavelength multiplexed signal after performing the frequency conversion.

5 . The signal detection device according to claim 1 ,

wherein the frequency conversion unit is configured to perform the frequency conversion, perform frequency conversion on an optical signal again, and then demultiplex a wavelength multiplexed signal.

6 . The signal detection device according to claim 1 ,

wherein the frequency conversion unit is configured to perform separation into a low frequency side and a high frequency side, perform frequency conversion by an optical parametric process on each branch, and then demultiplex a wavelength multiplexed signal.

7 . A signal detection method performed by a signal detection device, comprising:

converting N (N is a natural number) spatial mode signals including a plurality of higher modes excited in a transmission path fiber into N base modes and outputting the N basis modes;

converting N optical signals into frequencies different from each other;

multiplexing the N optical signals having frequencies that have been converted; and

photoelectrically converting a multiplexed optical signal while maintaining modulation information for a phase and polarization, performing digital signal conversion and signal processing, and demodulating an original information sequence.

8 . A non-transitory computer-readable storage medium storing a program for causing a computer to:

convert N (N is a natural number) spatial mode signals including a plurality of higher modes excited in a transmission path fiber into N base modes and output the N basis modes;

convert frequencies of respective N optical signals into frequencies different from each other;

multiplex the N optical signals having frequencies that have been converted; and

photoelectrically convert a multiplexed optical signal while maintaining modulation information for a phase and polarization, perform digital signal conversion and signal processing, and demodulate an original information sequence.