Temperature control system for a grating

A temperature control device for controlling temperature distribution of a grating of a variable dispersion equalizer, the temperature control device comprising:

• a controller for controlling temperatures of a plurality of electrical heaters with respective control signals to produce a plurality of temperature distribution patterns of the grating, each temperature distribution pattern being a respective combination of the control signals for the heaters;
• first and second control signal setting devices independently setting first and second variable control signals applied to the plurality of heaters;
• and
• a signal adding device for adding the first and second control signals supplied by the respective control signal setting devices to produce respective summed control signals, and transmitting the summed control signals to the respective heaters, providing independent control of the heaters for each of two variables related to the first and second control signals.

A temperature control device for controlling temperature distribution of a grating of a variable dispersion equalizer, the temperature control device comprising:

• a controller for controlling temperatures of a plurality of electrical heaters with respective control signals to produce a plurality of temperature distribution patterns of the grating, each temperature distribution pattern being a respective combination of the control signals for the heaters;
• a photoelectric conversion unit for photoelectrically converting an optical signal, reflected by the grating of the optical waveguide, into an electrical signal;
• and
• an operation device for comparing the electrical signal with a predetermined value to produce a difference signal and for controlling electrical power applied to a respective heater in response to the difference signal so that the electrical signal is changed to become not less than the predetermined value.

A method of automatically controlling a temperature control device for independently controlling each of a plurality of heaters which are disposed near a grating of a variable dispersion equalizer for an optical waveguide, the method comprising:

• converting an optical signal reflected by the grating into an electrical signal;
• comparing the electrical signal with a predetermined value;
• adjusting a control signal applied to the respective heaters such that the electrical signal becomes a value which is not less than the predetermined value;
• and
• controlling the respective heaters with the control signal.