What does it mean for a laser to have a 'high energy density'?

For a laser to have a 'high energy density' means that it can deliver a significant amount of energy into a very small area. This characteristic is essential for various applications, particularly in fields like medicine and materials processing, where precision is critical. The ability to concentrate energy in a small spot allows for increased effectiveness in tasks such as cutting, welding, or ablating materials, and can lead to better outcomes in procedures like laser surgery.

In contrast, lower energy density would imply that the laser light is spread out over a larger area, which could compromise its effectiveness in achieving the desired results. The other options, while they describe different laser attributes or implications, do not accurately capture the essence of what high energy density signifies in practical use.