LiDAR Space

The diode-pumped alkali laser (DPAL) is a gas laser pumped by laser diodes. Only a few percent of the pump energy becomes heat. The gain medium is a flowing gas. It has no crystal or fiber to distort, and the flow carries the heat away. The output is in the near infrared, where the atmosphere transmits well. At that wavelength a beam director forms a smaller spot than it would at one micron. These advantages have kept researchers working on the DPAL for two decades.

The pump has been the main obstacle. The spectrum of a laser diode is about a thousand times wider than the absorption line of the alkali atoms. The conventional remedy is pressure broadening, at high pressure and high temperature. That remedy costs much of the advantage. The upper-state lifetime of the alkali atoms is also too short to store energy, so alkali lasers have been continuous-wave lasers.

LiDAR Space has removed these obstacles one at a time. First, a patented external cavity with an atomic-line filter locks the pump diodes to the alkali line. The laser can then run at low pressure. Second, a ring resonator puts the low-power return beam on its own path, where mode-control optics can be placed. Third, a folded multipass path stores energy in a circulating pulse. Fourth, the pump can run in short, bright bursts, because the atomic-line filter locks instantly. The result is a low-pressure, pulsed DPAL.

The technology serves two missions, both power-scalable: solar-suppressed sensing, applied first to detecting and tracking small objects in low Earth orbit in daylight, and ablative effects delivery, applied first to countering uncrewed aircraft. Both apply on land, at sea, in the air, and in space.

The company is based in Durham, New Hampshire, is a member of the Joint Directed Energy Consortium, and is eligible for SBIR Phase III awards.