What is the wavelength of a laser?
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Wavelength of a Laser
Laser is an acronym for 'light amplification by stimulated emission of radiation'. Lasers produce coherent light, which means the light waves are synchronized in phase and frequency. The wavelength of a laser determines its color in the visible spectrum or its position in the electromagnetic spectrum if the wavelength is outside the visible range.
How is Laser Wavelength Defined?
The wavelength of a laser is the distance between successive peaks (or troughs) of its waves, typically measured in nanometers (nm) for visible light, or sometimes in micrometers (µm) when referring to infrared or ultraviolet light.
Factors determining the Wavelength of a Laser
- Active medium: The material used in the laser's gain medium – such as crystals, gases, or semiconductors – has specific energy transitions that determine the wavelength of the emitted light.
- Pump source: The source of energy used to excite the atoms in the gain medium can influence the possible wavelengths or modes the laser can operate in.
- Cavity design: The optical resonator or cavity that stores the light contains mirrors that are specific to wavelength, ensuring feedback of the correct wavelength light.
Common Wavelength Ranges for Different Types of Lasers
| Laser Type | Wavelength Range |
|---|---|
| Ultraviolet Lasers | 100 nm - 400 nm |
| Visible Light Lasers | 400 nm - 700 nm |
| Infrared Lasers | 700 nm - 1 mm |
| Terahertz Lasers | 1 mm - 100 mm |
Applications Based on Laser Wavelength
- Ultraviolet: Used in lithography, surgery, and disinfection.
- Visible: Common in laser pointers, barcode scanners, and fiber-optic communications.
- Infrared: Employed in remote controls, telecommunications, and laser cutting.
- Terahertz: Utilized in security scanning and spectroscopy.
Thus, the wavelength of a laser beam is a fundamental characteristic that affects its interaction with materials and its applications in a wide range of fields.