We develop a theoretical model of multimode rate equation that accurately describes mode evolution mechanism of prelase Q-switched Pr3+:YLF single longitudinal mode (SLM).The theoretical simulation process explained each part of the operation and experimental phenomenon in the pre-lase process effectively.We identify that there is an optimal parameter for the two step signal of acoustic-optic modulator which determines the stability of SLM output.Our theoretical model can be applied to most solid-state lasers, and offer theoretical references for the design and construction of experimental facilities, which is significant for future research.Up to now, there is still not a complete theory to accurate description of prelase Q-switching technology. Moreover, there have been no reported about directly emitting Q-switched SLM laser in the visible region.
In this paper, the multi-wavelength Šolc-type filter based on MgO:APLN (aperiodically poled lithium niobates) is studied theoretically and simulated. The sequences of the domains in MgO:APLN are optimized to realize the prescribed multiple wavelengths filtering using the novel algorithm. In single domain of MgO:APLN, the output electric field component is calculated by using Runge-Kutta method, which is used as the initial electric field component of the next domain. The output electric field component is obtained by iterative above operation, and finally the transmittance of Šolc-type filter is calculated. The transmittance characteristics of Šolc-type filter at 1470nm and 1570nm under different polarization structures are simulated. It is found that when the applied electric field is 120V/mm and the crystal nonlinearity coefficient is 1:1, the transmittance of 1470 and 1570 nm can reach at 100%. Furthermore, while maintaining the crystal polarization structure, the transmittance of Šolc-type filter under different electric fields is simulated, and it is found that the transmittance of 1470nm and 1570nm increases with the applied electric field intensity, that is, the modulation of transmission power by applied electric field is realized. The accuracy of this method is verified by experiments. This method is suitable for the optimization design of any multi-band Šolc-type filter and provides theoretical support for the development of WDM, DWDM and HSRL.
In this paper, we presented a widely tunable Mid-IR OPO based on a single multiple periods MgO:PPLN crystal, acousto-optical (AO) Q-switched Nd:YVO4 laser pumped by 880 nm laser diode (LD) was used as the pumping source. The OPO was designed as an extracavity single resonant optical parametric oscillator. When the grating period of the MgO:PPLN crystal was 31.5 μm and working temperature of 100°C, and the pump power was 10.95 W with repetition rate of 50 kHz, the single wavelength of 1.72 μm and idler wavelength of 2.78 μm was obtained respectively, the maximum average output power of the parametric lasers was 3.02 W, the pulse width of 7.9 ns was achieved. The optic-optic conversion efficiency was 27.58% from the 1064 nm pump laser to the parametric lasers. By tuning the grating period (28.5~31.5 μm) and the working temperature (25~192.1°C) of the MgO:PPLN, the single laser can be tuned from 1.46 μm to 1.72 μm, the corresponding idler laser can be tuned from 2.40 μm to 4.17 μm.
A mid-infrared optical parametric oscillator (OPO) with an idler wavelength of 3.85 μm at a repetition rate of 200 kHz is presented, and a high-repetition-rate electro-optic (EO) Q-switched Nd∶GdVO 4 laser with a double-crystal RbTiOPO 4 EO modulator is used as the pump source. The OPO is designed as an extracavity singly resonant optical parametric oscillator. The threshold value of the OPO system is only 1.3 W at 1.06 μm. When the MgO: periodically poled lithium niobate (MgO: PPLN) crystal is operated at 90°C and the pump power is 10.5 W with a repetition of 200 kHz, a maximum average output power of 1.82 W at idler wavelength of 3.85 μm and pulse width of 14.3 ns are obtained. The slope efficiency of the 3.85-μm laser with respect to the pump laser is 21.3%. The M 2 factors of the 3.85-μm laser are 1.84 and 1.76 in the parallel and perpendicular directions, respectively. The mid-infrared tunability of 3.7 to 3.9 μm can be achieved by adjusting the temperature of MgO∶PPLN crystal from 210 to 35°C.
In this paper, we present a compact 803 nm diode side-pumped Nd:YAP laser that can produce 86 W of polarized
1341.4 nm output in continuous-wave mode. The laser characteristics including thermal lens and different cavity
types were studied. By comparing the output powers at different resonator lengths and different output couplers, 86
W output power with c-axis polarized laser at 1341.4 nm has been obtained at the maximum pumping power of 840
W. The optical-optical efficiency is 10.2% and the slope efficiency is 16.6%. The beam quality factors of the 1341.4
nm laser are 13.26 and 13.54 in the parallel and perpendicular directions, respectively.
We report on a LD dual-end-pumped 792nm continuous wave operation Tm:YLF laser. Firstly, the rate equation of LD end-pumped CW operation Tm:YLF laser were established, in which the energy transfer upconversion and without energy transfer upconversion under continuous-wave considerate were considered, as well the pump threshold and the slope efficiency of the laser system were analyzed. Simultaneously, the cavity stability condition and the pattern matching of the plano- concave resonator were analyzed according to ABCD Matrix theory. Comparing respectively the laser threshold and the slope efficiency and optical-optical conversion efficiency under circumstances which the output mirror transmittance of 15% and 23%. In addition, the M2 of the output laser were contrasted and analyzed in adjusting the resonator cavity length by using different radius of curvature of the output mirror in 150mm, 200mm and 300mm all in the above case. As the process of thermal lens focal length changing greater than 90mm, it exhibited that the two fundamental modes in the cavity resonator matched well in numerical simulation when the radius of curvature of the output mirror was 300mm, as well the two fundamental modes matched well when it more than 100mm in a certain pump power. We designed a single LD dual-end-pumped continuous wave operation Tm:YLF laser. Using Tm:YLF (3 at.%) crystal for gain medium, which the size was 3×3×14mm3. In experiments, the Tm:YLF laser crystal keeps 291K and the temperature control method is water cooling. The length of the resonator was 135mm when L shape plano-concave resonator was applied, and the radius of curvature output mirror was 300mm, as well as the temperature of the Tm:YLF laser crystal was 291K. The output laser we observed by this system and the central laser wavelength was 1944nm. The threshold power was 8.11W and the highest output power reaches to 4.01W when the totally input pump power was 17W, and the optical conversion efficiency was 23.6%. The far-field divergence angle was 3.8mrad after calculation. Respectively. The experimental results are coinciding with the theory.
Recently, continue-wave blue laser generated by frequency doubling of the diode-end pumped neodymium doped
lasers operating at the 4F3/2→4I9/2 transition have been extensively explored. But this way is limited by the
considerable re-absorption loss caused by thermal population of the lower laser level for the oscillation of
quasi-three-level laser. Another efficient way to obtain blue laser is based on summing frequency of the neodymium
doped laser operating at the 4F3/2→4I13/2 transition. Unlike the three-level system of the 4F3/2→4I9/2 transition,
stimulated emission at the 4F3/2→4I13/2 transition is a four-level system that can provide a low-threshold and stable
laser output due to the lack of sensitive temperature dependence of the transition rate. High power blue laser has
been achieved in this way. In this paper, we report a high power blue laser output is obtained by intracavity
sum-frequency-mixing of a diode-side-pumped Q-switched Nd:YAP laser operating at 1.3μm with two LBO crystals.
An LBO crystal with type-I critical phase matching and the other crystal with type-II critical phase matching were
used for the second harmonic generation and the third harmonic generation, respectively. In view of the analysis of
the cavity stability, a four-mirror folded cavity was designed and the output characteristics were theoretically
analyzed. Experimental characteristics obtained were shown to be in agreement with the theoretical analysis. 3.2W
average power at 447nm and 1.3W average power at 446nm blue laser outputs were achieved at 1kHz with pulse
width of 10ns from the 1341.4nm laser beam polarized along the c crystalline axis and the 1339.2nm laser beam
polarized along the a crystalline axis, respectively. The 447nm blue laser corresponds to a red-to-blue conversion
efficiency of 30%.
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