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So that the intensity of the light pulses from a SESAM poor greater, then the top-level reflection light pulses superimposed on the pulse modulation of a light pulse through the combined effects of SESAM absorption and linear amplification of the laser gain medium, the oscillation of the pulse sequence effective option. Identification of laser intensity began to compress the pulse width, but the cavity of the laser pulse energy is not enough to SESAM completely bleached, and due to the spontaneous emission of the laser cavity to produce self-Q-clamping. With the oscillation of the laser pulse in the cavity, the cavity seed pulse sad gradually strengthen enough to SESAM bleaching light pulse by the depth of the SESAM modulation. Recently, a kind of green laser star pointer becomes the favorite of the customers.
Play a major role at this stage is the SESAM with heat relaxation process, the SESAM with heat balance of time is very short, the interband transition time can be ignored. The SESAM underlying reflex nonlinear absorption of the pulse back at the top-level mirror reflection of the pulse interference superimposed in order to achieve the modulation of amplitude and phase at the same time. Strong pulse modulated through the gain medium, the medium into the nonlinear amplification stage, front and center parts of the amplified due to the loss of population inversion, the gain decreased pulse along the amplification of less or even not amplification, steepening around along with the result that, pulse narrowing, small pulse was almost completely inhibited, thereby to output a series of high intensity, pulse width of the pulse sequence. The customer can replace the batteries from the middle part of  green laser star pointer.
Of Nd: YV04 crystal. Nd: YV04 (hunger acid Ming) crystals with strong birefringence positive uniaxial crystal, the tetragonal symmetry (4/mmm) wrong cristobalite (ZrSi04,) structure. Nd: YV04 crystal by using the appropriate Nd3 + ions replace the location of the y3 + ion formed in the in YV04 matrix growth process. Activated ion Nd3 + the location of the crystal with low point-group symmetry, the intensity of the ion oscillation. The YV04 matrix sensitization of Nd +3 and improve the absorption capacity of the activated ions. Since 1966, the Nd: YV04 crystal is widely recognized as an important laser materials. The level structure of the Nd: YV04 crystal. Figure 1.2 shows the energy level structure diagram of the Nd: YV04 crystal. The pre-acceptance and final acceptance of star laser pointer should be carried out by the customer in the location of the manufacturer.
Life is very short when using 808nmLD pump, the pump light particles from the ground state excitation to energy levels, the particles of the 4F2 / 5 level, through the non-radiation relaxation process can be very fast falling level 4F312 . 4F3 / 2 level is a metastable level, the energy level relatively long-lived, prone to aggregation number of particles, and thus below the level to achieve population inversion. Particles on the metastable level 4P3 Nepalese by the stimulated transition to the low energy level to radiation of different wavelengths of laser, Nd: YV04 crystal has four main emission lines: 4p312-411S / 2,4 FM-113 / 2,4 Fm of-4IlI / 2,4 p312-419/2, corresponding to the radiation wavelength, respectively 1.839um 1.342um 1.064 households m and 0. 914um. In case that some problems happen during use of green laser star pointer.
Which at room temperature 1.064um spectrum emission cross-section, gain the most of a spectral line, 1.34um, followed by the weakest it is 1.839ILm and 0.914um. In fact, due to the Nd3 + ions by the matrix crystal field, the main level will produce Stark splitting, accurate radiative transition occurs between the different sublevels. Of Nd: YV04 ground state energy level Stark splitting is only 439 mm on. The 914nm transition usually quasi-three-level transition. Figure 1.3 Nd: YV04 crystal polarized absorption spectra. Figure 1.3 gives the Nd: YV04 crystal polarized absorption lines. It can be seen from the figure that the absorption of crystals of π polarized light (parallel to the crystal c-axis) is greater than σ polarized light (perpendicular to the crystal C axis) absorption. Actually, some other specific functions can be added to green laser star pointer.