Optical transmitter, optical transmission/reception system, and drive circuit

摘要

An optical modulator includes optical waveguides on which phase modulation regions are formed. A drive circuit includes a lower-bit drive unit, an upper-bit drive unit, and a bit splitting unit. The bit splitting unit splits an input digital signal into upper bits and lower bits. The lower-bit drive unit outputs a value obtained by performing D/A conversion on the lower bits to phase modulation regions. The upper-bit drive unit outputs, to phase modulation regions, a value greater than a maximum value of values output from the lower-bit drive unit, or a minimum value of the values output from the lower-bit drive unit, according to a value of the upper bits.

主权项

1. An optical transmitter comprising:
an optical modulator including an optical transmission line through which an optical signal propagates, a plurality of phase modulation regions being formed on the optical transmission line; and a drive circuit that outputs a driving signal to each of the plurality of phase modulation regions according to an input digital signal, wherein the drive circuit includes:
a bit splitting unit that splits the input digital signal into upper bits and lower bits;a lower-bit drive unit that outputs, as a driving signal, a value obtained by performing D/A conversion on the lower bits, to a first phase modulation region of the plurality of modulation regions; andan upper-bit drive unit that outputs, to a phase modulation region different from the first phase modulation region, a value greater than a maximum value of the driving signal output from the lower-bit drive unit, or a minimum value of the driving signal output from the lower-bit drive unit, as a driving signal, according to a value of the upper bits,wherein the lower-bit drive unit includes a 2n (n is an integer equal to or greater than 2)-level first DAC that performs D/A conversion on an n-bit signal, the n bits being the lower bits.