Multiwatt mid-IR output from a Nd:YALO laser pumped intracavity KTA OPO

Hybrid Q-switched laser with MoS2 saturable absorber and AOM driven sub-nanosecond KTP-OPO

Two-dimensional (2D) materials, especially transition-metal dichalcogenides, such as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂), have attracted great interests due to their exceptional optical properties as saturable absorbers in laser systems. In this work, at first, we presented a diode-pumped passively Q-switched laser with MoS₂ saturable absorber (MoS₂-SA). At an incident pump power of 6.54 W, a maximum output power of 1.15 W with a minimum pulse duration of 70.6 ns was obtained, which is the shortest pulse duration of diode pumped passively Q-switched laser with MoS₂-SA to the best of our knowledge. Then, by using a hybrid Q-switched laser with a MoS₂-SA and an acousto-optic modulator (AOM) as pumping fundamental laser, a sub-nanosecond KTiOPO₄ (KTP) based intracavity optical parametric oscillation (IOPO) was realized. With an incident pump power of 10.2 W and AOM repetition rate of 10 kHz, the maximum output power of 183 mW with minimum pulse duration of 850 ps was obtained. The experimental results indicate that the IOPO pumped by the hybrid Q-switched laser with AOM and MoS₂-SA can generate signal wave with shorter pulse duration than those IOPOs pumped by hybrid Q-switched laser with AOM and Cr⁴⁺:YAG or single-walled carbon nanotube saturable absober (SWCNT-SA) or monolayer graphene SA.

Comparative study of intracavity KTP-based Raman generation between Nd:YAP and Nd:YAG lasers operating on the (4)F(3/2) → (4)I(13/2) transition

Extending the spectral wavelengths of the diode-pumped Nd-doped lasers at 1.3 μm with the KTP crystal in the intracavity Raman configuration is reported for the first time to the best of our knowledge. A systematic comparison is performed to show that a better optical conversion efficiency for the Nd:YAP/KTP Raman laser could be achieved thanks to the higher peak power and linearly polarized radiation at 1341 nm, whereas up to four Stokes emission lines are generated from the Nd:YAG/KTP Raman laser as a result of the fundamental dual-color operation at 1319 and 1338 nm. The maximum Stokes output power of the developed Nd:YAP/KTP Raman laser reaches 1.04 W under an incident pump power of 16 W and a pulse repetition rate of 10 kHz, corresponding to the diode-to-Stokes conversion efficiency as high as 6.5%. The largest pulse energy and highest peak power are evaluated to be up to 104 μJ and 34.7 kW, respectively.

Theoretical and experimental studies on output characteristics of an intracavity KTA OPO

An acousto-optically Q-switched Nd:YVO(4)/KTiOAsO(4) (KTA) intracavity optical parametric oscillator (OPO) is efficiently realized in singly resonated scheme. With an end-pumping diode power of 25.9 W, output signal (1535 nm) power of 3.77 W and idler power (3467 nm) of 1.18 W are obtained at a pulse repetition rate of 50 kHz. A rate-equation model is set up to simulate the output power and time characteristics of both signal and idler waves. And both the numerical and experimental results show that the idler pulse width is shorter than the signal one in a singly resonant OPO.

Influence of the time modulation of the pump laser caused by mode beating on optical parametric process

Numerical simulation and analysis about the influence of the time modulation of the pump laser caused by mode beating on optical parametric process are presented with OPA and OPG as examples. It is shown that the output power of the generated beams from optical parametric process is modulated in the time domain and exhibits large power fluctuations, when a Q-switched laser oscillating on several random longitudinal modes is used as the pump laser. Irregular spike sequences of the generated beams are observed. We also find that the output power of the light from optical parametric process becomes more stable and exhibits a less fluctuation, when the number of the longitudinal modes (n) increases.

High-efficiency intracavity Nd:YVO4\KTA optical parametric oscillator with 3.6 W output power at 1.53 microm

An efficient intracavity KTA optical parametric oscillator (OPO) driven by diode-end-pumped acousto-optical Q-switched Nd:YVO(4) laser is demonstrated. The mode mismatch between fundamental cavity and OPO cavity caused by the thermal lens effect in Nd:YVO(4) crystal as the pump power increased was studied. To lessen mode mismatch, a thermal lens-like cavity mirror made of plane BK7 glass induced by idler absorption was introduced into the OPO cavity. Under a diode pump power of 20 W, a maximum 1535nm light output power of 3.6 W was achieved at the pulse repetition rate of 60 kHz, corresponding to a diode-to-signal conversion efficiency of 18%. This is the highest efficiency reported for eye-safe laser based on intracavity OPO.

Coexistent optical parametric oscillation and stimulated Raman scattering in KTiOAsO4

Coexistent optical parametric oscillation (OPO) and stimulated Raman scattering (SRS) are demonstrated in an X-cut KTiOAsO(4) (KTA) crystal. The 30-mm-long KTA crystal is placed within a diode-end-pumped acousto-optically (AO) Q-switched Nd:YAG laser cavity to construct an intracavity optical parametric oscillator. Coexistent Raman conversion of the fundamental wave is observed from the KTA crystal. With a diode power of 7.43 W and a pulse repetition rate (PRR) of 20 kHz, a signal (1535.0 nm) power of 0.92 W is obtained, corresponding to a diode-tosignal conversion efficiency of 12.4%. A first-Stokes (1091.4 nm) power of 0.17 W is obtained.

Compact KTA-based intracavity optical parametric oscillator driven by a passively Q-switched Nd:GdVO4 laser

We present a compact and efficient KTA-based intracavity optical parametric oscillator (IOPO) driven by a diode-end-pumped Nd:GdVO(4)/Cr:YAG passively Q-switched laser. At the incident diode pump power of 9.2 W, signal (1.53 microm) and idler (3.47 microm) average output powers of up to 744 and 356 mW, respectively, have been obtained. The total (signal+idler) optical-to-optical conversion efficiency is as high as 12%. By using the knife-edge method, near-diffraction-limited signal and idler beams have been detected, and the M(2) factors are well within 1.2. In addition, based on the ABCD matrix theory, the impact of mode matching and the thermal lens effect on the OPO output have been analyzed.