Abstract: An external cavity diode laser has been developed to achieve a linear frequency chirp over a broad bandwidth using a silicon photonic filter chip as the external cavity. By appropriately chirping the cavity phase using the gain chip and/or a cavity phase modulator on the silicon photonic chip along with simultaneously varying the filter resonance, approximately linear frequency chirping can be accomplished for at least 50 GHz, although desirable structures with useful lesser chirp bandwidths are also described. With careful control of the chip design, it is possible to achieve predictable behavior of mode jumps along with large scannable ranges within a mode, which allows for stitching together segments of linear chirp through a mode jump to provide for very large chirp bandwidths greater than 1 THz.

Abstract: An apparatus including a reference resistor for use with ratiometric temperature sensing of a device to be sensed. The resistive element has a resistance dependant upon a temperature of the device to be sensed and is electrically coupled to a reference resistor. The reference resistor is maintained at a substantially constant temperature by a temperature controller. A sensor circuit is electrically coupled to the resistive element and the reference resistor to sense their electrical parameters when a current passes through them.

Abstract: In one embodiment of the present invention, an apparatus operates a control loop for a tunable optical device. A digital reference signal is converted to an analog reference signal and then introduced into the optical path of the tunable optical device. An analog feedback signal, corresponding to the digital reference signal, is recovered from the tunable optical device. The analog feedback signal is converted to a digital feedback signal. The apparatus sends tuning information to the tunable optical device based on analysis of the digital reference signal and the digital feedback signal. In one embodiment, the tuning information is used for wavelength locking of the tunable optical device. In another embodiment, the operation of the control loop is synchronized with another function of the tunable optical device.

Abstract: Tunable laser systems use servo control loops to control and monitor laser parameters such as channel, temperature, and power. The many control loops operate asynchronously, which means that noise generated by input sampling and/or output updating from one or more loops could interfere with the sampled inputs of one or more of the other loops. Embodiments of the present invention synchronize setting and sampling of tunable laser parameters to reduce noise. Noise that is related to synchronized setting and sampling of tunable laser parameters allows the noise to be reduced to constant offsets to be compensated for in the laser parameters of interest.

Abstract: A tunable optical unit includes a resistive temperature device (RTD), a thermal tuning device and a measurement circuit. The RTD has a resistance dependent on a temperature of the thermal tuning device. The measurement circuit outputs a signal that is dependent on the resistance of the RTD. The signal is used to control the temperature of the thermal tuning device in tuning the tunable optical unit. A reference resistance can be connected in series with the RTD to make ratio-metric measurements to determine the RTD's resistance (and hence the temperature of the tuning elements) without having to know the value of the current conducted through the RTD and to reduce sensitivity to fluctuations in the excitation signal.

Abstract: A tunable optical unit includes a resistive temperature device (RTD), a thermal tuning device and a measurement circuit. The RTD has a resistance dependent on a temperature of the thermal tuning device. The measurement circuit outputs a signal that is dependent on the resistance of the RTD. The signal is used to control the temperature of the thermal tuning device in tuning the tunable optical unit. A reference resistance can be connected in series with the RTD to make ratio-metric measurements to determine the RTD's resistance (and hence the temperature of the tuning elements) without having to know the value of the current conducted through the RTD and to reduce sensitivity to fluctuations in the excitation signal.

Abstract: An apparatus including a reference resistor for use with ratiometric temperature sensing of a device to be sensed. The resistive element has a resistance dependant upon a temperature of the device to be sensed and is electrically coupled to a reference resistor. The reference resistor is maintained at a substantially constant temperature by a temperature controller. A sensor circuit is electrically coupled to the resistive element and the reference resistor to sense their electrical parameters when a current passes through them.

Abstract: In one embodiment of the present invention, an apparatus operates a control loop for a tunable optical device. A digital reference signal is converted to an analog reference signal and then introduced into the optical path of the tunable optical device. An analog feedback signal, corresponding to the digital reference signal, is recovered from the tunable optical device. The analog feedback signal is converted to a digital feedback signal. The apparatus sends tuning information to the tunable optical device based on analysis of the digital reference signal and the digital feedback signal. In one embodiment, the tuning information is used for wavelength locking of the tunable optical device. In another embodiment, the operation of the control loop is synchronized with another function of the tunable optical device.

Abstract: Tunable laser systems use servo control loops to control and monitor laser parameters such as channel, temperature, and power. The many control loops operate asynchronously, which means that noise generated by input sampling and/or output updating from one or more loops could interfere with the sampled inputs of one or more of the other loops. Embodiments of the present invention synchronize setting and sampling of tunable laser parameters to reduce noise. Noise that is related to synchronized setting and sampling of tunable laser parameters allows the noise to be reduced to constant offsets to be compensated for in the laser parameters of interest.

Abstract: The present invention provides an optical signal generator for use in calibrating and testing optical components. The optical signal generator utilizes a tunable laser in conjunction with a novel modulation circuit to output an analog/digital optical signal. The modulator circuit combines a low-frequency, closed loop power control with a separate digital modulator. The output beam of the tunable laser may be modulated over a wide range of frequencies, duty cycles and amplitudes. Circuitry is also provided for modulation of an analog signal onto the output.