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How is a narrow linewidth laser?

How is a narrow linewidth laser?

Feb 11, 2021

Single-frequency laser with very narrow radiation spectrum


Some laser applications require a laser with very narrow linewidth, that is a narrow spectrum. Narrow linewidth lasers refer to single-frequency lasers, that is, there is a resonant cavity mode in the laser value, and the phase noise is very low, so the spectral purity is high. Usually this kind of laser has very low intensity noise.


Type of narrow linewidth laser:


The most important types of narrow linewidth lasers are as follows:


1. Semiconductor lasers, distributed feedback laser diodes (DFB lasers) and distributed Bragg reflector lasers (DBR lasers), the most reusable ones are applied in the 1500 or 1000 nm region. Typical operating parameters are output power of tens of milliwatts (sometimes greater than 100 milliwatts) and line width of several MHz.


2. The line width obtained by the semiconductor laser may be narrower, and an ultra-narrow line width of a few kHz or even less than 1 kHz can be achieved.


3. A small distributed feedback fiber laser (the resonator is composed of a special fiber Bragg grating) can generate tens of milliwatts of output power, and the line width is in the range of several kHz.


4. Diode-pumped solid-state bulk lasers with non-planar ring resonators can also obtain linewidth of several kHz, while the output power is relatively high at around 1W.

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Main factors affecting the narrow linewidth laser:


First, single-frequency operation.


Second, it is necessary to minimize the influence of external noise.


Third, the laser design needs to be optimized to minimize laser noise, especially the phase noise.


Application of narrow linewidth laser:

1). Sensing


2). Optical frequency measurement 


3). Transmitters, detection or measurement.


The narrow-linewidth semiconductor laser must be small, lightweight, highly insensitive to vibrations, demonstrate great performance related to power spectral density of frequency noise (PSDFN), and offer very good value for money. 

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Elite Optoelectronics provides high-quality OEM&ODM laser diode modules with ultra-narrow linewidth covering the wavelength range of 375 nm-980 nm.For more, please contact us at 86-29-68590616 or sale@s-laser.com