80-W single-frequency Innoslab µs-amplifier at 1319†nm with high efficiency.

A single-frequency quasi-continuous-wave partially end-pumped slab (Innoslab) laser amplifier at 1319 nm was demonstrated. The 3-W single-frequency all-fiber seed laser was amplified to a maximum average power of 80.1 W and the power stability was 0.52% in 10 minutes. The corresponding optical-optical efficiency was 16.1% under absorbed pump power of 478 W. The output pulse width was 131 µs at the repetition of 500 Hz. The beam quality factors of M2 were 1.3 in both the vertical and horizontal directions. To the best of our knowledge, this is the first report on single-frequency Nd:YAG Innoslab amplifier at 1319 nm with such high output power and efficiency.

170-W Nd:YAG InnoSlab laser at 1319†nm.

In this paper, a continuous-wave Nd:YAG InnoSlab laser at 1319 nm with high output power and high beam quality is demonstrated. The maximum output power of 170 W at 1319-nm single wavelength is obtained with an optical-to-optical efficiency of 15.3% from absorbed pump power to laser output and the corresponding slope efficiency of 26.7%. The beam quality factors of M2 are 1.54 and 1.78 in the horizontal and vertical directions, respectively. To the best of our knowledge, this is the first report on Nd:YAG 1319-nm InnoSlab lasers with such high output power and good beam quality.

Influence of Sand Production Damage in Unconsolidated Sandstone Reservoirs on Pore Structure Characteristics and Oil Recovery at the Microscopic Scale.

Unconsolidated sandstone reservoirs have low rock strength and are easily damaged by sand production. To evaluate the effect of the microscopic pore system on the degree of recovery and sand production damage, five typical unconsolidated sandstone core samples were selected. The nuclear magnetic resonance T2 spectrum of the water-flooding experiments was used to analyze the oil displacement mechanism and sand production damage of the pore throat structure, and the control mechanism of the injection parameters was used to evaluate the recovery and sand production damage degree. The results showed that the recovery of the unconsolidated sandstone core samples was the highest when the injection volume was 6 PV, and the overall pore throat recovery increased from 14.37 to 48.72%. The recovery and sand production damage increased with increasing injection pressure. The overall pore throat recovery was the highest when the pressure was 20 MPa (48.42%), and the sand production damage index was the maximum when the pressure was 25 MPa (19.98%). Under a lower injection pressure, sand production damage mainly originates from loose sand. The main target of loose sand production damage is a smaller pore throat, and the sand production index increases slowly. The recovery increased with the pressure and increased relatively quickly. Under a higher injection pressure, sand production damage mainly comes from loose sand and skeleton sand, causing damage to both smaller and larger pore throats. The sand production damage is positively correlated with injection pressure. The recovery slows down with an increase in pressure or even decreases.

300 W two-stage Nd:YAG Innoslab microsecond amplifier.

In this paper, a two-stage partially pumped slab (Innoslab) microsecond amplifier at 1064 nm is reported. The 4.4-W single-frequency seed laser is amplified to 303.6 W, with an overall optical-optical efficiency of 25.7%. The overlapping efficiency of the first- and second- amplifier stage is 67% and 55.6%, respectively. The pulse width is 145.0 µs, at a repetition rate of 500 Hz, and the beam quality factor of M2 is 1.84 and 1.71 in the horizontal and vertical directions, respectively. With higher overlap between the pump volume and the seed laser mode, the output power and optical-optical efficiency can be further improved.

148-W single-frequency Nd:YAG Innoslab µs-amplifier at 1064†nm with high efficiency.

In this paper, a single-frequency quasi-continuous-wave partially pumped slab (Innoslab) amplifier at 1064 nm is reported. The 4.4-W single-frequency seed laser was amplified to 148.1 W with optical-optical efficiency of 30.4%. The output pulse duration was 141.4 µs at the repetition of 500 Hz. The beam quality factors of M2 were 1.41 and 1.37 in the horizontal and vertical direction respectively. The experimental results match well with the numerical simulation. To the best of our knowledge, this is the first report on single-frequency Nd:YAG Innoslab amplifier with such a high output power and efficiency.

110 W 1678 nm laser based on high-efficiency optical parametric interactions pumped by high-power slab laser.

This Letter presents a high-efficiency optical parametric amplifier pumped by a high-power slab laser with approximate uniform rectangular distribution. By optimizing the overlapping, spectrum matching, and pulse synchronization for the pump and signal lasers, output power of 110.8 W at 1678 nm with corresponding conversion efficiency of 32.3% was achieved in addition to sufficient usage of the effective area in MgO doped periodically poled lithium niobate crystal. It could also provide a designable and tunable wavelength of the amplified laser in a wide infrared region.

High-power and widely tunable mid-infrared optical parametric amplification based on PPMgLN.

We report on a high-power and widely tunable optical parametric amplifier (OPA) based on PPMgLN and pumped by a pulsed 1.064 µm MOPA laser. The operating wavelength of the OPA system is continuously tunable from 2.68 to 3.07 µm by adjusting the temperature of PPMgLN crystals, with average output power varying from 74.6 to 66.7 W for 310 W of pump power, corresponding to an optical-to-optical conversion efficiency of ∼22.8% at 2.68 µm and ∼20.5% at 3.07 µm, respectively. Output beam quality factor (M2) of the OPA was measured to be <4 over the whole tuning range.

High-power, narrow-bandwidth mid-infrared PPMgLN optical parametric oscillator with a volume Bragg grating.

We report on a high-power, narrow spectral bandwidth 2.907 µm PPMgLN optical parametric oscillator (OPO) pumped by a 1.064 µm pulsed Nd:YAG MOPA laser source. Free-running operation of the OPO exhibits maximum average output power of 71.6 W at 2.907 µm with a slope efficiency of 26.7%. Broad 2.907 µm spectral bandwidth of the free-running OPO was suppressed from ~9 nm to less than 0.7 nm by using a VBG as one cavity mirror. The maximum average power was 51.7 W at 2907.55 nm for the spectrum-narrowed OPO, corresponding to a slope efficiency of 22.5%. Continuously tunable ranges of ~8 nm around 2.907 µm had been achieved via adjusting the temperatures of the VBG and PPMgLN accordingly.