Source: Nature
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Understanding Thresholdless Lasers

What are Thresholdless Lasers?

Thresholdless lasers are a type of laser that operate with an extremely low or essentially zero threshold pump power. This means that they can start lasing with very little input power compared to traditional lasers.

How Do They Work?

The concept of thresholdless lasers involves forcing spontaneous emission to occur primarily into the spatial mode defined by the laser resonator. This is achieved by using a microcavity around the gain medium, which alters the mode structure of the gain medium’s environment. By ensuring that emission is directed into the laser mode with the highest Q factor, thresholdless behavior can be achieved.

Experimental Demonstrations

Over the years, various types of lasers with very low threshold powers based on the thresholdless principle have been developed. Examples include vertical cavity surface-emitting lasers with remarkably low threshold currents and photonic crystal nanolasers with ultra-low threshold pump powers. Additionally, the concept of a single-atom laser has shown thresholdless behavior, showcasing intricate quantum optics phenomena.

Future Implications

The development of thresholdless lasers opens up possibilities for highly efficient and low-power laser technologies. These lasers could find applications in areas requiring low energy consumption and compact laser sources, such as in telecommunications, sensing, and quantum technologies.

Source: Nature
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