Electro-absorption modulated laser with high operating temperature tolerance

A transmitter for an optical communication system, the transmitter comprising:

• a) a laser that generates light at an output;
• b) an electro-absorption modulator having an electrically controllable absorption, the electro-absorption modulator comprising a semiconductor layer that is optically coupled to the output of the laser, a material composition of the semiconductor layer being chosen so that a transmission response of the modulator as a function of applied voltage shifts with an increasing operating temperature of the modulator so that the semiconductor layer is substantially transparent to light propagating through the semiconductor layer when a substantially zero or a reverse bias voltage is applied across the semiconductor layer at operating temperatures of the electro-absorption modulator that are substantially greater than 25 degrees Celsius;
• c) an electronic data modulator having an output that is electrically coupled to a modulation input of the electro-absorption modulator, the electronic data modulator generating an AC electrical modulation signal having a peak-to-peak voltage amplitude that changes an absorption edge of the semiconductor layer, thereby changing light transmission characteristics of the electro-absorption modulator and modulating the light generated by the laser;
• d) a thermal sensor that is in thermal communication with at least one of the semiconductor layers of the electro-absorption modulator and the laser;
• and
• e) a temperature-driven controller having an input that is electrically coupled to the thermal sensor and an output that is electrically coupled to a DC bias control input of the electronic data modulator, the temperature-driven controller generating a signal that causes the electronic data modulator to change a DC bias voltage of the AC electrical modulation signal.

A method of modulating light, the method comprising:

• a) applying a DC reverse bias voltage across a semiconductor layer having an electrically controllable absorption;
• b) propagating light through a semiconductor layer having an electrically controllable absorption, a transmission response of the semiconductor layer as a function of applied voltage shifting with an increasing operating temperature of the semiconductor layer so that the semiconductor layer is substantially transparent to light propagating through the semiconductor layer when a substantially zero or a reverse bias voltage is applied across the semiconductor layer at operating temperatures of the electra-absorption modulator that are substantially greater than 25 degrees Celsius;
• and
• c) applying an AC electrical modulation signal having a peak-to-peak voltage amplitude across the semiconductor layer, the modulation signal changing an absorption edge of the semiconductor layer, thereby modulating the light.

A method of tracking a temperature of an electro-absorption modulator to a temperature of a semiconductor laser, the method comprising:

• a) generating light with a semiconductor laser;
• b) propagating the light through an electro-absorption modulator comprising a semiconductor layer having an electrically controllable absorption, a material composition of the semiconductor layer being chosen so that a transmission response of the modulator as a function of applied voltage shifts with an increasing operating temperature of the modulator so that the semiconductor layer is substantially transparent to light propagating through the semiconductor layer when a substantially zero or a reverse bias voltage is applied across the semiconductor layer at operating temperatures of the electro-absorption modulator that are substantially greater than 25 degrees Celsius;
• c) applying an AC electrical modulation signal having a DC reverse bias voltage and a peak-to-peak voltage amplitude across the semiconductor layer, the modulation signal changing an absorption edge of the semiconductor layer, thereby changing light transmission characteristics of the electro-absorption modulator and modulating the light generated by the laser;
• d) measuring a temperature or the semiconductor laser that generates the light;
• and
• e) changing at least one of the DC reverse bias voltage and the peak-to-peak voltage amplitude of the AC electrical modulation signal, and a bias current through the laser in response to the measured temperature.