Laser transmits an invisible light beam at a frequency (technically, a "Wavelength") of 905 nanometers. A nanometer is the unit of length used to measure light wavelength.
Since laser guns use a specific light frequency or wavelength, it is possible to detect a laser's signature light pulse rates. Different laser guns operate at different light pulse rates. Some competitors call them "bands". All Whistler radar/laser detectors receive all current laser guns in use.
Keep in mind that laser detectors act differently than radar detectors. Since the narrow laser beam produces very little "scatter"- random bits of electromagnetic energy bouncing down the road -it is much harder to detect than a powerful radar gun that blankets the countryside with easily detectable microwave signals. Laser guns operate exclusively in instant-on mode and usually target vehicles at short range. Typically an officer will aim the laser at a vehicles' license plate or headlights, and the beam is only 3 feet wide at the point of impact. Accordingly, if you are the target vehicle don't expect much warning. The distance from where your detector is mounted to the license plate can be greater than 3 feet. This will be outside of the laser beam. If the officer is not steady while targeting vehicles, scatter laser signals can result, giving a possible signal to detect.