Optical transmitter and method for controlling operation state of optical transmitter

An optical transmitter, comprising:

• a plurality of ring waveguides optically coupled in cascade;
• an electrode which is formed near the ring waveguides and is provided with a signal;
• a first waveguide optically coupled to one of the ring waveguides located at one end of the ring waveguides;
• a second waveguide optically coupled to another of the ring waveguides located at the other end of the ring waveguides without optically being coupled directly to the first waveguide;
• and
• a light source configured to supply continuous wave light to the first waveguide, wherein
• a modulated optical signal that is generated in the ring waveguides based on the signal provided to the electrode is outputted through the second waveguide.

An optical transmitter including a plurality of ring resonator-based transmitters and a bus waveguide, wherein:

• each ring resonator-based transmitter comprises:
• a ring waveguide;
• an electrode which is formed near the ring waveguide and is provided with a signal;
• an input waveguide which is optically coupled to the ring waveguide;
• and
• a light source configured to supply continuous wave light to the input waveguide;
• wavelengths of continuous wave light generated by the light sources of respective ring resonator-based transmitters are different from one another, and
• the ring waveguides of respective ring resonator-based transmitters are optically coupled to the bus waveguide, wherein
• modulated optical signals that are respectively generated in the ring waveguides based on the signals provided to the electrodes are outputted through the bus waveguide.

An optical modulator, comprising:

• a ring waveguide;
• an electrode which is formed near the ring waveguide and is provided with a signal;
• a first waveguide which is optically coupled to the ring waveguide, continuous wave light being input to the first waveguide;
• and
• a second waveguide which is optically coupled to the ring waveguide without being optically coupled directly to the first waveguide, wherein
• a modulated optical signal that is generated in the ring waveguide based on the signal provided to the electrode is outputted through the second waveguide.

A method for controlling an optical transmitter that includes a ring waveguide, an electrode formed near the ring waveguide, a first waveguide optically coupled to the ring waveguide, a second waveguide optically coupled to the ring waveguide without being optically coupled directly to the first waveguide, and a light source which supplies continuous wave light to the first waveguide from a first end of the first waveguide, the method comprising:

• monitoring an optical level at a second end of the first waveguide while applying a specified voltage to the electrode;
• controlling the temperature of the ring waveguide such that the monitored optical level is smaller;
• and
• generating a modulated optical signal in the ring waveguide by supplying a signal to the electrode to output the modulated optical signal through the second waveguide after the monitored optical level is minimized in the controlling process.