LASER is the acronym for "Light Amplification by Stimulated Emission of Radiation." This study aims to clarify the principles and fundamental elements of lasers.
We conducted a non-systematic literature review without time restriction using the PubMed/Medline, Scopus, and Cochrane databases, searching for publications addressing laser technology itself. A narrative synthesis is presented.
A laser consists of modified light made of photons with the same wavelength or color (monochromaticity) and direction. The production of laser radiation is based on the principles of stimulated emission within an optical cavity made up of two mirrors containing an amplifying medium (gas, liquid, or solid) excited by a pumping source (electric arc, flash lamps, or diode). Numerous configurations, and therefore beam properties, are available for various medical and non-medical applications. Laser emissions can be continuous or pulsed. In the first case, laser radiation is characterized by constant average power. Pulsed emission delivers bursts of laser radiation separated in time by intervals without emission. The pulse is characterized by its energy (J), its duration (s), and therefore an instantaneous power (W, where the maximum corresponds to peak power). One can also define average power (Watts) as the product of the energy per pulse (J) and the frequency (Hz) of their emission.
Lasers consist of monochromatic and unidirectional light being emitted continuously or on a pulsed mode. The beam properties - peak power, pulse duration, energy, and frequency - influence the physical phenomena of laser-matter interaction.
The French journal of urology. 2025 Nov [Epub]
Frederic Panthier, Laurent Berthe, Olivier Traxer, Nadia Abid, Christophe Almeras, Steeve Doizi
Endolase Lab, GRC n(o) 20-Sorbonne Université, PIMM Lab Arts et Métiers ParisTech, 75020 Paris, France; Service d'Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Tenon, Sorbonne Université, 75020 Paris, France; PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151, boulevard de l'Hôpital, 75013 Paris, France; Endourology Technology Section of European Association of Urology (EAU), Arnhem, The Netherlands; Progressive Endourological Association for Research and Leading Solutions (PEARLS), Paris, France. Electronic address: ., Endolase Lab, GRC n(o) 20-Sorbonne Université, PIMM Lab Arts et Métiers ParisTech, 75020 Paris, France; Service d'Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Tenon, Sorbonne Université, 75020 Paris, France; PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151, boulevard de l'Hôpital, 75013 Paris, France., Endolase Lab, GRC n(o) 20-Sorbonne Université, PIMM Lab Arts et Métiers ParisTech, 75020 Paris, France; Service d'Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Tenon, Sorbonne Université, 75020 Paris, France; PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151, boulevard de l'Hôpital, 75013 Paris, France; Endourology Technology Section of European Association of Urology (EAU), Arnhem, The Netherlands; Progressive Endourological Association for Research and Leading Solutions (PEARLS), Paris, France., Department of Urology and Transplant Surgery, Hospices civils de Lyon, Edouard-Herriot Hospital, 5 place d'Arsonval, 69003 Lyon, France., Department of Urology, La Croix du Sud Clinic-RGDS, UroSud, 52 bis Chemin de Ribaute, Boite 301, 31130 Quint-Fonsegrives, France., Endolase Lab, GRC n(o) 20-Sorbonne Université, PIMM Lab Arts et Métiers ParisTech, 75020 Paris, France; Service d'Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Tenon, Sorbonne Université, 75020 Paris, France; PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech, 151, boulevard de l'Hôpital, 75013 Paris, France; Endourology Technology Section of European Association of Urology (EAU), Arnhem, The Netherlands; Sorbonne Université, GRC n(o) 39, Santé de l'homme, Hôpital Tenon, 75020 Paris, France.