The linewidth of a laser, especially a single-frequency laser, refers to the width of its spectrum (typically full width at half maximum, FWHM). More precisely, it is the width of the radiated electric field power spectral density, expressed in terms of frequency, wavenumber, or wavelength. The linewidth of a laser is closely related to temporal coherence and is characterized by coherence time and coherence length. If the phase undergoes an unbounded shift, phase noise contributes to the linewidth; this is the case with free oscillators. (Phase fluctuations confined to a very small phase interval produce zero linewidth and some noise sidebands.) Shifts in the resonant cavity length also contribute to the linewidth and make it dependent on the measurement time. This indicates that the linewidth alone, or even a desirable spectral shape (lineform), cannot provide the full information about the laser spectrum.
VBG technology (Volume Bragg Grating) is an optical filtering and wavelength control technology based on the three-dimensional periodic refractive index modulation of photosensitive materials. Its core applications include laser wavelength locking, linewidth narrowing, and beam shaping, and it is widely used in high-power lasers, pump sources (such as 976nm/980nm laser diodes), and fiber optic communications.
The principle of lasers is based on stimulated emission, a concept first proposed by Einstein in the early 20th century. The main process is as follows.
According to the different transmission point moduli, optical fibers can be divided into single-mode fibers and multi-mode fibers. The so-called "mode" refers to a beam of light entering the optical fiber at a certain angular velocity.
Box Optronics launched a 1550nm, 100mW, 100kHz narrow-linewidth DFB laser diode in a 14-pin butterfly package with integrated TEC temperature control and monitoring PD.
TEC coolers essentially utilize the Peltier effect to directly convert electrical energy into thermal energy. They are a solid-state refrigeration technology that requires no mechanical motion.
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