1.4 ?m Human Eye Safety Laser Based On Nd:LGGG Crystal

When a laser light incidents on the eyes, with the wavelength is 1.4?m, most power of the laser light is absorbed by the aqueous humor and lens components, as a result,small amount of power can reaches the retina, that is, the eye itself has a self-protection mechanism. In this paper, we introduced a passively Q-switched eye-safe laser, with the new crystal Nd: LGGG as the gain medium and the graphene as the saturable absorber.we also study its applications, espesially the characteristics of output light laser, whose wavelengh is 1.4?m. Contrast to the active Q eye-safe laser, the passively eye-safe Q-switched laser has a series of advantages, such as the simpler structure, less weight and better reliability.1. This paper comprehensively introduces the development of solid-state lasers, with the principles and the classification of Q- swapping. And we completed the theoretical and mechanical designs of eye-safe laser, with the wavelengh is 1.4m.2. We briefly describs a series properties of the Nd: LGGG crystal, including its structure, the growth method, the thermal properties, the spectroscopic properties and absorption characteristics. As its strongest absorption peak at 805 nanometers and the maximum width at half maximum is 8.6 nm, the Nd: LGGG crystal is a perfect construction as the gain medium, without stringent temperature requiring.3. We also introduces the graphene's mechanism of nonlinear absorption and saturable absorption to light, and the graphene passively Q-switched laser characteristics. As the Q-switched pulses time is shorter than the saturation graphene relaxation time, it belongs to the saturated faster graphene saturable absorber.4. Using graphene as the saturable absorber, we study the graphene passively Q-switched Nd: LGGG laser to obtain 1.4?m eye-safe laser output for the first time.When the injection pump power is 14.3 W, we can get of 1.4?m Q tunable laser output, with the average power is 255 m W, the pulse width is 490 nanoseconds, the largest single laser pulse energy is 3.2 J, and the pulse peak power is 6.53 W.5. The main innovations of our study is that we get a wavelength of 1.4?m laser pulse output and the width of the laser pulse can be obtained as 490 nanoseconds, with the Nd:LGGG as the laser gain medium and the graphene as the saturable absorber for the first time.