Passively Q-Switched and mode-locked Nd:YVO<Subscript>4</Subscript> laser with sandwich structured wallpaper graphene oxide absorber

We report on a passively Q-switched and mode-locked Nd:YVO₄ laser using a novel low-cost wall-paper graphene oxide absorber. Sandwich structured wallpaper graphene oxide absorber was constructed by a high transmission mirror, a piece of wallpaper graphene oxide absorber and a reflective mirror. The average output power of 310 mW of passively Q-switched and mode-locked laser was successfully achieved. The repetition rate and pulse width of the Q-switched envelope were 213 kHz and 770 ns, respectively. The repetition rate of passively mode-locked pulse within the Q-switched envelope was 81.3 MHz with the pulse energy of 3.8 nJ.     

Analysis of a laser-diode end-pumped intracavity frequency-doubled passively Q-switched and mode-locked Nd:GdVO<Subscript>4</Subscript>/KTP laser with a semiconductor saturable absorber

A diode-pumped passively Q-switched mode-locked (QML) intracavity frequency-doubled Nd:GdVO₄/KTP green laser with a semiconductor saturable absorber is presented. Nearly 100% modulation depth for the mode-locked green pulses can be achieved at any pump power over 1.92 W. The width of the mode-locked green pulse was estimated to be about 150 ps. The mode-locked pulse interval within the Q-switched envelope of 320 ns and the repetition rate of 97.5 kHz were obtained, at an incident pump power of 4.4 W. The repetition rate of the mode-locked green pulses inside the Q-switched envelope was 140 MHz.     

Diode-pumped passively Q-switched and Q-switch mode-locked Nd:YVO<Subscript>4</Subscript> laser using single-wall carbon nanotube based saturable absorber

We present the performance of diode end-pumped Nd:YVO₄ laser in Q-switched and Q-switched mode-locking oscillation using a single-walled carbon nanotube based saturable absorber, which was fabricated using similar vertical evaporation technique. The average output power, repetition rate and pulse width of the Q-switched laser output were studied with different output couplers. The maximum average output power was 130 mW. For Q-switched mode-locking operation, the repetition rate of the mode-locked pulses concentrated in the Q-switched envelope was 58 MHz. The repetition rate of the Q-switched envelope maintained at 18 kHz, while the pulse width decreased along with the increasing of pump power. The maximum average output power was 53 mW.     

Diode-pumped passively Q-switched and mode-locked Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> laser with a GaAs saturable absorber

By using a-cut Nd:Lu_0.15Y_0.85VO₄ mixed crystal as laser gain medium, a diode-pumped passively Q-switched and mode-locked (QML) laser with a GaAs saturable absorber in a Z-type folded cavity is demonstrated for the first time. The Q-switched mode-locked laser pulses with about 90% modulation depth are obtained as long as the pump power reached the oscillation threshold. The repetition rate of the passively Q-switched pulse envelope ranges from 50 to 186 kHz as the pump power increases from 0.915 to 6.520 W. Under an incident pump power of 6.52 W, the QML pulses with the largest average output power of 694 mW, the shortest pulse width of 200 ns and the highest pulse energy of 3.73 μJ are obtained. The mode-locked pulse width inside the Q-switched envelope is estimated to be about 275 ps. The experimental results show that Nd:Lu_0.15Y_0.85VO₄ is a promising mixed crystal for QML laser.     

Diode-pumped simultaneously Q-switched and mode-locked Nd:GdVO<Subscript>4</Subscript>/LBO red Laser

A diode-end-pumped simultaneously Q-switched and mode-locked intracavity frequency doubled Nd:GdVO₄/LBO red laser with an acousto-optic Q-switch was realized. The maximum red laser output power of 250 mW was obtained at the incident pump power of 8.3 W and the repetition rate of 10 kHz. At 5 kHz, the maximum mode-locking modulation depth of about 80% was achieved with the Q-switched pulse width of 440 ns. The red mode-locked pulse inside the Q-switched pulse had a repetition rate of 115 MHz, its average pulse width was estimated to be about 350 ps.     

Q-switched and mode-locked diode-pumped Nd:YVO4 laser with an intracavity composite semiconductor saturable absorber

We have demonstrated a passively Q-switched and mode-locked Nd:YVO₄ laser with an intracavity composite semiconductor saturable absorber (ICSSA). Stable Q-switched and mode-locked pulses with Q-switched envelope pulse duration of 180 ns and pulse repetition rate of 72 KHz have been obtained. The maximum average output power was 1.45 W at 8 W incident pump power. The repetition rate of the mode-locked pulses inside the Q-switched envelope was 154 MHz. Experimental results revealed that this ICSSA was suitable for Q-switched and mode-locked solid-state lasers.     

Stable Q-switch mode-locking of Nd:YVO<Subscript>4</Subscript> lasers with a semiconductor saturable absorber

This paper reports on a passively mode-locked and Q-switched Nd:YVO₄ laser generating picosecond pulses with an average output power exceeding 7 W. In a first step Q-switch mode-locking was obtained by self Q-switching of a mode-locked oscillator with appropriate cavity design, pump power and output coupling. In a second system the Q-switching was actively controlled and stabilized by modulating the resonator internal losses with an acousto-optic modulator. In the Q-switch mode-locking operation the laser provided 12.8 ps long mode-locked pulses with a repetition rate of 80 MHz. The repetition rate of the Q-switch envelope was 185 kHz. The maximum pulse energy of a single ps pulse was 0.55 μJ which is 5.5 times the pulse energy measured for cw mode locking. The total energy of the pulses within the Q-switch envelope was 42 μJ. PACS  42.55.Xi; 42.60.Fc; 42.60.Gd     

Experimental study on doubly QML Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> laser with AO modulator and central SESAM

By using double-mixed crystal Nd:Lu_0.15Y_0.85VO₄ as laser medium, a diode-pumped doubly Q-switched and mode-locked (QML) Nd:Lu_0.15Y_0.85VO₄ laser with acousto-optic (AO) modulator and central semiconductor saturable absorption mirror (SESAM) is realized for the first time. The Q-switched envelope modulation depth is nearly 100%.The average output power and the pulse width of the Q-switched envelope etc. for different AO modulator repetition rates have been measured. The experimental result show that Nd:Lu_0.15Y_0.85VO₄ crystal is an excellent laser medium for doubly QML lasers.     

Simultaneous Q switching and mode locking with narrow envelope width in a microchip Nd:YVO4 laser with a composite semiconductor absorber

By using a composite semiconductor absorber and an output coupler, we demonstrated a Q-switched and mode-locked diode-pumped microchip Nd:YVO₄ laser. With a 350-μm-thick crystal, the width of the Q-switched envelope was as short as 12 ns; the repetition rate of the mode-locked pulses inside the Q-switched pulse was more than 10 GHz. The average output power was 335 mW at a maximum pump power of 1.6 W. Q-switched envelope widths of 21 and 31 ns were also achieved with crystals 0.7 and 1.0 mm thick, respectively.     

Diode-pumped passively Q-switched mode-locked Nd:LuVO4 laser with a semiconductor saturable absorber mirror

We present a compact passively Q-switched mode-locked Nd:LuVO₄ laser run in a Z-type folded cavity with semiconductor saturable absorber mirror (SESAM). The repetition rates of the passively Q-switched pulse envelope ranges from 22.99 to 141.18 kHz as the pump power increased from 2.372 to 8.960 W. The repetition rates of mode-locked laser pulses in the Q-switched pulse envelope has 111 MHz determined by the cavity length and the mode-locked pulse duration is evaluated to be 257 ps. An average output power of 823.5 mW is achieved at the pump power of 8.96 W, corresponding to an optical conversion efficiency of 9.2%.     

Passively Q-switched and mode-locked diode-pumped Nd:YVO4 laser with LT-GaAs output coupler

We have demonstrated an efficient and compact passively Q-switched and mode-locked (QML) 1064 nm Nd:YVO₄ laser by using a low temperature grown GaAs (LT-GaAs) saturable absorber as well as an output coupler. Stable QML with envelope duration as short as 10 ns and Q-switched repetition rate of 36 kHz was obtained. It is the shortest envelope duration as far as we know, and it is so short that it can be used as Q-switching pulses directly. At 6.9 W of the incident pump power, average output power of 1.24 W was achieved and the corresponding peak power and energy of a single Q-switched pulse were 3.44 kW and 34.4 μJ, respectively. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of 780 MHz.     

Passively Q-switched mode-locking in a diode-pumped Nd:LuVO<Subscript>4</Subscript> laser with V:YAG

A passively Q-switched and mode-locked Nd:LuVO₄ laser with V:YAG at 1.34 μm was successfully demonstrated. Comparisons between c-cut and a-cut Nd:LuVO₄ lasers were experimentally made. The maximum average output power of 170 mW, the highest Q-switched pulse energy of 4.5 μJ were obtained in c-cut Nd:LuVO₄ laser. The duration of mode-locked pulse was estimated to be less than 540 ps with repetition rate of 110 MHz.     

LD side-pumped high beam quality passive Q-switched and mode-locked Nd:YAG laser based on SESAM

We report a LD side-pumped fundamental-mode (Mx² = 1.35 and My² = 1.27) passive Q-switched and mode-locked Nd:YAG laser based on a semiconductor saturable absorber mirror (SESAM). At a pump current of 12.5 A, the average output power of 5.68 W with 80 kHz repetition rate and 2 μs pulse width of the Q-switched envelope was generated. The repetition rate of the mode-locked pulse within the Q-switched envelope of 88 MHz was achieved.     

Q-switched and continuous-wave mode-locking of a diode-pumped Nd:Gd0.64Y0.36VO4−Cr4+:YAG laser

We report on a diode-pumped passively mode-locked Nd:Gd_0.64Y_0.36VO₄ laser with a Cr⁴⁺:YAG saturable absorber. Q-switched mode locking (QML) with 90% modulation depth was obtained. The peak power of the mode-locked pulse near the maximum of the Q-switched envelope was estimated to be about 1.7 MW at the pump power of 12 W. Besides QML, continuous-wave mode locking was also experimentally realized, for the first time to our knowledge, in the laser under a strong intracavity pulse energy fluence. The mode-locked pulse width is about 2.96 ps at a repetition rate of 161.3 MHz.     

LD-pumped 1.34 μm-Q-switched and mode-locked Nd:GdVO4 laser by a V3+:YAG saturable absorber

A diode-pumped passively Q-switched and mode-locked Nd:GdVO₄ laser at 1.34 μm with V³⁺:YAG as the saturable absorber is realized in a V-type folded cavity. About 100% modulation depth of mode locking can be obtained as long as the pump power reaches the oscillation threshold. The width of the mode-locked pulse is estimated to be less than 280 ps with 200 MHz repetition rate within an about 980 ns-long Q-switched pulse envelope. A maximum output power of 200 mW and Q-switched pulse energy of 5.7 μJ is obtained.     

Performance of 2 μm Tm:YAP pulse laser based on a carbon nanotube absorber

We demonstrated the first use of carbon nanotube as a saturable absorber in the Q-switched and Q-switched mode-locking of a diode pumped Tm:YAP operating at 2 μm. At the incident pump power of 8.64 W, the minimum Q-switched pulse width of 255.1 ns, and the maximum peak power 53.1 W can be obtained with the corresponding repetition rate of 21.76 kHz. The performance of a diode-pumped passively Q-switched mode-locked Tm:YAP laser with high repetition rate formed with a folded cavity. As high as 780 mW average output power was produced in QML laser. The repetition rate of the mode-locked pulse inside the Q-switched envelope was 244.1 MHz. The dependence of the operational parameters on the pump power was also investigated experimentally.     

Passive mode-locked Nd:YVO<Subscript>4</Subscript> laser using a multi-walled carbon nanotube saturable absorber

We report a passive mode-locked Nd:YVO₄ laser pumped by 880 nm LD using a transmission-type multi-walled carbon nanotube saturable absorber. At the pump power of 6.1 W, the average output power of 0.8 W of continuous wave mode-locked laser with optical conversion efficiency of 13.1% was generated. The repetition rate and pulse energy of the mode-locked pulse were 88 MHz and 9.1 nJ, respectively.     

Self-Q-switched and mode-locked 946 nm Cr,Nd:YAG laser

A simultaneous self-Q-switched and mode-locked diode-pumped 946 nm laser by using a Cr,Nd:YAG crystal as gain medium as well as saturable absorber is demonstrated for the first time as we know. The maximum average output power of 751 mW with a slope efficiency of 18.38% is obtained at an intra-cavity average peak power intensity of 4.83 × 10⁶ W/cm². Under this circumstance, the repetition rate of Q-switched envelopes is 9.63 kHz and the pulse width is about 460 ns. Almost 100% mode-locked modulation depth is obtained at all time in the experiment process whether the incident pump power is low or high. The repetition rate of mode-locked pulses within a Q-switched envelope is 135.13 MHz and the mode-locked pulse width is within 600 ps. The laser produces high-quality pulses in TEM₀₀-mode in the simultaneous self-Q-switched and mode-locked experiment.     

High-power passively Q-switched mode-locking Nd:GdVO4 laser with LT-InGaAs saturable absorber

The generation of passively Q-switched mode-locking (QML) pulse has been obtained from a diode-pumped Nd:GdVO₄ laser with a LT-InGaAs wafer as saturable absorber as well as output coupler. Under the incident pump power of 10 W, an average output power of QML was 1.8 W with a Q-switched repetition rate of 280 kHz. The pulse duration of Q-switched pulse is about 160 ns and mode-locked pulse within the Q-switched envelope had a repetition rate of 410 MHz. It is indicated that the present LT-InGaAs is a very promising device in the field of mode locking solid-state laser, and we are sure that it will be complete pure cw mode locking with single beam output easily after further optimizing in the parameter such as saturation fluence, modulation depth, recovery time and damage threshold in semiconductors.     

Diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG /KTP green laser

We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG green laser with a KTP crystal as the intra-cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170±20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.