Frequency scanning pulsed laser having synchronously set subthreshold current
AssigneeWilliam Marsh Rice University
InventorsAnatoliy A. Kosterev, Frank K. Tittel
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Abstract
The present invention provides methods and apparatus for flexible and reproducible control of quantum cascade laser frequency scans having short (nanosecond) pulse excitations. In accordance with a preferred embodiment of the invention, a method of digital frequency control for pulsed quantum cascade lasers includes digitally synthesizing a sub-threshold current, converting the sub-threshold current to analog form, and generating laser pulses. Preferably, the sub-threshold current is synchronized to the laser pulses.
Claims17
A system for spectroscopic analysis that comprises:
- a laser configured to receive an excitation signal having a subthreshold current component and a pulsed current component, wherein the laser has a subthreshold current frequency dependence;
- a digital controller that provides the subthreshold current component, wherein the digital controller alters the subthreshold current component in synchronization with pulses in the pulsed current component.
A method that comprises:
- generating a pulsed current signal having a series of current pulses;
- generating a digitally-controlled subthreshold current signal having a series of discrete current values that change synchronously with the series of pulses;
- combining the pulsed current signal with the digitally controlled signal to produce an excitation signal;
- and
- providing the excitation signal to a laser.
A method of detecting trace components of a gas, the method comprising:
- generating a digitally-controlled sequence of subthreshold current values in a subthreshold component signal;
- generating a pulse component signal having a sequence of pulses, wherein each pulse is generated a predetermined time after a change to the subthreshold component signal;
- combining the pulse component signal with the subthreshold component signal to form an excitation signal;
- and
- applying the excitation signal to a laser.
Dependencies are inferred from the claim text.