Laserlike

Laserlike is an informal descriptor used in optics and related fields to refer to light sources or emissions that resemble laser light in key aspects—most notably coherence, directionality, and spectral purity—but do not necessarily meet the formal criteria to be classified as a laser.

Typical laserlike characteristics include relatively high temporal coherence, narrow spectral linewidth, low beam divergence, and high brightness. The light may also be highly polarized and exhibit stable, quasi-monochromatic output over short to moderate durations.

The term is commonly applied to devices or phenomena such as superluminescent diodes, certain stimulated-emission sources operating outside strict laser thresholds, or laser‑like beams produced in nonlinear optical processes. It is also used in evaluating light sources for fiber-optic communication, sensing, and imaging where near-laser quality is advantageous but a true laser is unnecessary or impractical.

Because laserlike light does not always achieve full spatial coherence or long-term phase stability, its performance can degrade over long distances or under varying environmental conditions. The designation is subjective and can vary with operating parameters and context.

See also: coherence, laser, superluminescent diode, monochromatic light, beam quality.