Passively Q-switched solid-state lasers with intracavity optical parametric oscillators

Pulse Compression in Laser-Diode-Pumped Doubly Q-Switched Intracavity Optical Parametric Oscillator Considering Gaussian Distribution of Intracavity Photon Densities

“…In this section, an LD-pumped AO Q-switched IOPO with an intracavity saturable absorber is considered. If neglecting the spatial variation of the photon densities, and supposing the lasers are strictly homogeneously broadened, a series of rate equations can be obtained 7,23) where E j ðtÞ ( j = p, s, i) is electrical field of the pump laser for OPO (i.e., the fundamental light), the signal light, and the idler light, respectively; nðtÞ is the population inversion intensity of the laser rod; l, l g , l KTP , l OPO , and l y represent the physical length of the laser cavity, the gain medium, the KTP crystal, the OPO cavity, and the saturable absorber, respectively; l y can be expressed by l y ¼ Àðln T 0 Þ=ð g n y0 Þ, T 0 is the small-signal transmission of the saturable absorber. and are the stimulated-emission cross section and the stimulated-radiation lifetime of laser gain medium; t r is the round-trip time of the fundamental light; L is the intrinsic loss of the cavity; n y0 and n y1 ðtÞ are the population densities of the ground-state and the excited-state of the saturable absorber; g and e are the ground-state and the excited-state absorption cross section of the saturable absorber; y is the excited-state lifetime of the saturable absorber; !…”

“…Especially, when the nonlinear crystal KTP (KTiOPO 4 ) is pumped by a laser at the wavelength range from 1050 to 1070 nm, a signal laser whose wavelength is around 1.55 mm can be generated. [5][6][7][8] Recently, much attention has been paid to laser-diode (LD) end-pumped 1.57 mm intracavity optical paramatric oscillator (IOPO) [9][10][11][12] because of its low threshold and high efficiency in comparison with the extra-cavity OPO. 13,14) It is efficient to predict the performance of OPOs by means of rate equations.…”

“…The model given by Debuisschert et al 14) was simpler than those of the previous studies. Xiao et al 7) gave a more specific model of passively Q-switched lasers with an IOPO configuration. Peng et al 20) completed this model by considering thermally induced diffractive losses.…”

Comparison of Small-Scale Actively and Passively Q-Switched Eye-Safe Intracavity Optical Parametric Oscillators at 1.57 μm

“…Actually, IOPOs act very like cavity dumpers to fully and rapidly extract the pump energy into the signal and idler fields. [4] Therefore, KTP (or KTA)-based IOPOs with an emission around 1.5 µm and driven by nanosecond Nd-doped lasers are considered to be the most promising eye-safe laser sources in the near future. To operate a nanosecond IOPO more efficiently, a good Q-switching technique is often required to obtain a sufficiently great fundamental peak power.…”

Compact and Highly Efficient Passively Q -Switched Intracavity KTA-OPO at 1.53 and 3.47 μm

“…3, the residual energy is sufficiently high to create another or more satellite pulses, which has been recognized as multi-pulsing phenomenon. [21] The available energy is thus distributed in the consecutive signal pulses. Note that the threshold adjustment can be implemented by optimizing the signal reflectivity or choosing a proper initial transmission of the Cr:YAG saturable absorber.…”