Optical module

An optical module comprising:

• a light emitting device;
• a wavelength monitor chip monitoring backside light of the light emitting device;
• and
• a control unit controlling the light emitting device based on a monitoring result of the wavelength monitor chip,
• wherein the wavelength monitor chip includes
• a semiconductor substrate, and
• an optical coupler, an optical demultiplexer, first and second light receiving devices, a waveguide interferometer, and a phase modulation section which are formed on a surface of the semiconductor substrate,
• the optical coupler inputs the backside light as incident light,
• the optical demultiplexer splits the incident light into first branched light and second branched light,
• the first light receiving device receives the first branched light,
• the phase modulation section applies a pilot signal to light propagating through a ring waveguide of the waveguide interferometer,
• the second light receiving device receives the second branched light via the waveguide interferometer, and
• the control unit adjusts a current of the light emitting device so that a light receiving current of the first light receiving device becomes constant, obtains a value by dividing a modulated signal component of a light receiving current of the second light receiving device modulated in accordance with the pilot signal by the light receiving current of the first light receiving device, and adjusts temperature of the light emitting device so that the value becomes constant.

An optical module comprising:

• a light emitting device;
• a wavelength monitor chip monitoring backside light of the light emitting device;
• and
• a control unit controlling the light emitting device based on a monitoring result of the wavelength monitor chip,
• wherein the wavelength monitor chip includes
• a semiconductor substrate, and
• an optical coupler, first and second light receiving devices, a waveguide interferometer, and a phase modulation section which are formed on a surface of the semiconductor substrate,
• the optical coupler inputs the backside light as incident light,
• the first light receiving device is formed at a through port of the waveguide interferometer,
• the second light receiving device is formed at a cross port of the waveguide interferometer,
• the first light receiving device and the second light receiving device receive the incident light via the waveguide interferometer,
• the phase modulation section applies a pilot signal to light propagating through a ring waveguide of the waveguide interferometer, and
• the control unit controls a current of the light emitting device so that a sum of light receiving currents of the first light receiving device and the second light receiving device becomes constant, obtains a value by dividing a sum obtained by adding together, in opposite phases, modulated signal components of light receiving currents of the first and second light receiving devices modulated in accordance with the pilot signal by a sum of the light receiving currents of the first and second light receiving devices, and controls temperature of the light emitting device so that the value becomes constant.