Lesson plan
Random laser
In laser science, a random laser (RL) is a laser in which optical feedback is provided by scattering particles. As in conventional lasers, a gain medium is required for optical amplification. However, in contrast to Fabry–Pérot cavities and distributed feedback lasers, neither reflective surfaces nor distributed periodic structures are used in RLs, as light is confined in an active region by diffusive elements that either may or may not be spatially distributed inside the gain medium. The main principle behind a random laser is to increase the light path with disordered media; this can be done by diffusive disordered media or by using strong localization in a disordered media, with laser active background. Random lasing has been reported from a large variety of materials, e.g. colloidal solutions of dye and scattering particles, semiconductor powders, semiconductor polycrystalline thin films, optical fibers, polymers and biological tissue. Due to the output emission with low spatial coherence and laser-like energy conversion efficiency, RLs are attractive devices for energy efficient illumination applications. The concept of random lasing can also be time-reversed, resulting in a random anti-laser, which is a disordered medium that can perfectly absorb incoming coherent radiation.
Article summary
In laser science, a random laser (RL) is a laser in which optical feedback is provided by scattering particles. As in conventional lasers, a gain medium is required for optical amplification. However, in contrast to Fabry–Pérot cavities and distributed feedback lasers, neither reflective surfaces nor distributed periodic structures are used in RLs, as light is confined in an active region by diffusive elements that either may or may not be spatially distributed inside the gain medium. The main principle behind a random laser is to increase the light path with disordered media; this can be done by diffusive disordered media or by using strong localization in a disordered media, with laser active background. Random lasing has been reported from a large variety of materials, e.g. colloidal solutions of dye and scattering particles, semiconductor powders, semiconductor polycrystalline thin films, optical fibers, polymers and biological tissue. Due to the output emission with low spatial coherence and laser-like energy conversion efficiency, RLs are attractive devices for energy efficient illumination applications. The concept of random lasing can also be time-reversed, resulting in a random anti-laser, which is a disordered medium that can perfectly absorb incoming coherent radiation.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
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- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
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