Laser Basics
What a laser is and how it produces light, explained for first-time readers.
- Q-switching and mode locking: two ways to make short pulsesQ-switching stores energy and releases it at once. Mode locking gets many waves in step. This article explains both ideas with diagrams and shows why different things set the pulse length and spacing in each.
- Continuous-wave and pulsed lasersHow light that stays on (CW) differs from light that comes in bursts (pulsed), the four numbers that describe a pulse train, and why the same average power can give very different peak power.
- Laser safety: classes and how to read eyewear labelsWhat laser safety classes, maximum permissible exposure (MPE) and the wavelength and OD markings on eyewear mean, read with the conditions the official documents attach.
- Laser types at a glance: gas, solid-state, fiber, semiconductorLasers are grouped by gain medium into gas, solid-state, fiber and semiconductor types. One table gives each type's medium, pumping, typical wavelength and uses, and says where sources disagree.
- Light basics: waves, wavelength, frequency and photonsA high-school-level recap of wavelength, frequency, the speed of light, photon energy, and reflection, refraction and absorption, so the terms in the laser articles feel familiar.
- Oscillators and amplifiers: making light, then growing itWhy a laser can have one part that makes the light and another that makes it stronger, and what the MOPA layout is, explained with diagrams and public sources.
- Power, energy and intensity: W, J and W/cm²What power (W), energy (J) and intensity (W/cm²) each measure, shown with a light bulb and sunlight, and what a news report's "kW-class" does and does not tell you.
- The three parts of a laser: gain medium, pump and resonatorWhat the three basic parts of a laser (gain medium, pumping and resonator) each do, and how stimulated emission makes light grow, explained with diagrams and public sources.
- What is a laser? How it differs from a light bulbHow laser light differs from bulb light through three features (one direction, one color, in step), plus the meaning of the name, the first laser and common misunderstandings, based on public sources.
- Why wavelength matters: visible and invisible lightHow wavelength changes the color of light, whether you can see it, where it is absorbed in the eye, and how it passes through air, explained from public sources.
Articles in preparation
Listed in reading order. Titles may change. See the full reading path
- B10Interference and diffraction: how light adds up and spreadsLevel: BeginnerIn preparation
- B11Polarization: the direction in which light vibratesLevel: BeginnerIn preparation
- B12Why a beam spreads: divergence, focus and apertureLevel: BeginnerIn preparation
- B13Beam quality: M², divergence and brightnessLevel: IntermediateIn preparation