A chemical sensing system and method. The system (10) includes a transmitter (20) having a laser (200) for providing a collimated beam of electromagnetic energy at a first frequency and a Q switch (230) in optical alignment with the beam. The system further inlcudes a crystal for shifting the frequency of the beam from the first frequency to a second frequency. A mechanism is included for shifting the beam from the second frequency to a third frequency in the range of 8-12 microns. Ideally, the input beam is provided by a neodymium-YAG laser and the Q switch is a passive Q switch. The crystal is x-cut potassium titanyl arsenate. The system includes a mechanism for switching the polarization state of the second beam and providing third and fourth beams therefrom. The third beam has a first polarizaion and the fourth beam has a second polarization. The second polyrization is orthogonal relative to the first polarization. The mechanism for shifting the beam from the second frequency to the third frequency includes first and seccond optical parametric oscillators (250 and 271), each optical parametric oscillator including a cadmium selenide crystal. The frequency shifted third and fourth beams are combined to provide an output beam in the range of 8-12 microns. The output beam is transmitted and a return signal therefrom is detected by a receiver in the illustrative chemical sensing application.