Optical signal controller, optical signal control method, and optical signal transmission system

An optical signal control method of an optical signal control apparatus that controls a compensation coefficient of an equalizer of an optical transmitter including the equalizer of a symbol period interval and a digital-to-analog converter (DAC) operating at a symbol period interval sampling rate and having a sampling phase adjustment function, and a sampling phase of the DAC, the optical signal control method comprising:

• calculating a sampling phase amount from a group delay difference between an in-phase component and a quadrature component based on characteristic information, which includes a phase characteristic and an amplitude characteristic, of a device and a transmission path and outputting the calculated sampling phase amount to the DAC;
• calculating the compensation coefficient in which a phase amount of a Nyquist frequency of the DAC is 0 or an integer multiple of π and outputting the calculated compensation coefficient to the equalizer,
• compensating, by the equalizer, a transfer function of the device and the transmission path using the calculated compensation coefficient;
• and
• shifting, by the DAC, the phase characteristic of the in-phase component and that of the quadrature component by the group delay difference using the calculated sampling phase amount.

An optical signal transmission system comprising:

• an optical transmitter including an equalizer of a symbol period interval and a digital-to-analog converter (DAC) operating at a symbol period interval sampling rate and having a sampling phase adjustment function;
• and
• an optical signal control apparatus including a skew calculation unit configured to calculate a sampling phase amount from a group delay difference between an in-phase component and a quadrature component based on characteristic information, which includes a phase characteristic and an amplitude characteristic, of a device and a transmission path and to output the calculated sampling phase amount to the DAC and a compensation coefficient calculation unit configured to calculate the compensation coefficient in which a phase amount of a Nyquist frequency of the DAC is 0 or an integer multiple of π and to output the calculated compensation coefficient to the equalizer, wherein:
• the equalizer compensates a transfer function of the device and the transmission path using the calculated compensation coefficient;
• and the DAC shifts the phase characteristic of the in-phase component and that of the quadrature component by the group delay difference using the calculated sampling phase amount.