Research On 561nm All-Solid-State Low-Noise Laser

Because of the laser has four big advantages of high brightness, good coherence, directional well, good monochromaticity, so laser is widely applied to variety of fields. Wherein, the wavelength of 561 nm yellow-green laser has made tremendous contributions for the applications in medicine, it can cure eye disease which aspects are more difficult, and is one of many laser wavelengths which has best effect, it can also be used as a light source for the some biological imaging devices,confocal microscopy and flow cytometry to provide lighting. We main measure the noise of the output light, based on the measurement results to determine the quality of the laser. More lower the laser noise, the lower risk of instant rush of the output light intensity, the higher stability of laser power, and can reduce the damage for intracavity optical element, so as to prolong the working life of the laser. Therefore, research of the stable and low-noise 561 nm laser, so the band of laser will be able to apply in medicine more extensive, and it can make contribution for the advancement of medicine.In this paper, using a laser diode end pumped Nd:YAG crystal, LBO nonlinear crystal intracavity frequency doubling, with birefringent filter(BF)frequency-selecting, a stable low noise 561 nm output is obtained. The low noise561 nm laser output power is 70 m W when the pump power is 5W. The light to light conversion efficiency is 1.46%, signal to noise ratio for 0.93%. As a contrast, we select frequency with BP, the noise of 561 nm laser is higher than frequency-selecting by BF, signal to noise ratio for 12.5%. The experimental results show that noise control capability of the birefringent filter is better than BP, good at frequency selective ability, make the laser emit low noise, high brightness, yellow green laser.In addition, in the experimental process, I also used F-P etalon to measure the longitudinal mode of the output light of 561 nm double frequency laser which select frequency by birefringent filter, the experimental results show there are three longitudinal modes oscillating at the same time in the laser resonant cavity. This shows the BF not only can suppress the oscillation of other spectral lines, but also can reduce the laser longitudinal modes effectively, so the laser can operate under the low laser noise.