7 W laser diode end-pumped Nd:YVO<Subscript>4</Subscript> passively mode-locking laser with a semiconductor saturable absorber mirror

A powerful and stable LD end pumped Nd:YVO₄ passively mode-locking oscillator by SESAM was demonstrated. At the pumping power of 30 W, 7 W output was obtained with repetition rate of 79.5 MHz and pulse duration of 15 ps. The beam quality factors M ² were measured to be 1.30 and 1.33, respectively.     

Passively Q-switched laser operation in a composite Nd:YVO<Subscript>4</Subscript>/Nd:YVO<Subscript>4</Subscript>/Nd:YVO<Subscript>4</Subscript> crystal with a single-walled carbon nanotube saturable absorber

By using a piece of single-walled carbon nanotube saturable absorber, the performance of the passively Q-switched composite Nd:YVO₄ laser has been demonstrated for the first time. The maximum average output power and the shortest pulse width are 1220 mW and 103 ns at the incident pump power of 5.04 W for a 10% transmission of the output coupler. The highest pulse repetition rate of 415.6 kHz and the largest single-pulse energy of 2.94 μJ are also obtained. The composite Nd:YVO₄ crystal has more excellent laser performance than the normal Nd:YVO₄ crystal at 1064 nm.     

Continuous-wave passively mode-locked Nd:YVO<Subscript>4</Subscript>/KTP green laser with a semiconductor saturable absorber mirror

A diode-pumped passively mode-locked low-doped Nd:YVO₄ green laser with a semiconductor saturable absorber mirror (SESAM) and an intracavity frequency-doubling KTP crystal is demonstrated. In order to efficiently release the thermal effect, a low-doped Nd:YVO₄ crystal with the Nd³⁺ concentration of 0.1 at % is employed as the gain medium. The maximum average output power of 3.1 W at 532 nm with a repetition rate of 102 MHz is obtained under the pump power of 25 W, corresponding to an optical conversion efficiency of 12.4%. The 532 nm mode locked pulse width is estimated to be approximately 6.1 ps.     

A passively mode-locked Nd:YVO<Subscript>4</Subscript> laser with a carbon nanotube saturable absorber

We report the mode locking of a diode pumped Nd:YVO₄ crystal laser by using a transmission-type single-walled carbon nanotube saturable absorber. The laser operated at 1064 nm pumped by a fiber coupled laser diode with the cavity length of 1826 mm, generated a pulse width of 14 ps at a repetition rate of 82 MHz. The output power of 120 mW was obtained at the absorbed pumping power of 1400 mW.     

Diode-pumped passively Q-switched Nd:YVO<Subscript>4</Subscript> laser with a carbon nanotube saturable absorber

A diode end-pumped passively Q-switched Nd:YVO₄ laser with a transmission-type single-walled carbon nanotube saturable absorber is first demonstrated in this paper. The maximum continuous wave (CW) output power of 477 mW is obtained at the incident pump power of 1490 mW with the output transmission T = 10%, resulting in slope efficiency of 41.3%. For Q-switching operation, the measured pulse duration of 332 ns, the pulse energy of 326 nJ and the peak power of 982 mW are respectively obtained.     

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.     

High-repetition-rate megawatt millijoule pulses from a Nd:YVO<Subscript>4</Subscript> laser passively Q-switched by a semiconductor saturable absorber

We exploit an AlGaInAs periodic quantum-well absorber with a large modulation strength to realize a multi-mJ passively Q-switched Nd:YVO₄ laser with a repetition rate up to 200 Hz. At a pump energy of 34 mJ, the output pulse energy and the peak power are found to be 3.5 mJ and 1.1 MW, respectively. The fluctuation of the output pulse energy is generally less than ±2%.     

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.     

Quantum dot saturable absorber for passive mode locking of Nd:YVO<Subscript>4</Subscript> lasers at 1064 nm

An InAs/GaAs quantum dot saturable absorber mirror was used to mode lock a Nd:YVO₄ solid-state laser at the operation wavelength of 1064.6 nm. Multi-watt average power was obtained during stable cw mode locking with pulses as short as 24 ps, and with a repetition rate of 65 MHz. PACS 45.55.-f; 78.67.Hc; 42.60.Fc     

High power passively mode-locked Nd:YVO<Subscript>4</Subscript> laser using graphene oxide as a saturable absorber

We report on a passively mode-locked Nd:YVO₄ laser using a novel graphene oxide saturable absorber fabricated by vertical evaporation method. An 880 nm LD pump source was used to reduce the thermal load of the laser crystal. At the pump power of 7.4 W, 1.2 W average output power of continuous wave mode-locked laser with optical conversion efficiency of 16.2% was achieved. To the best of our knowledge, this is the highest output power of passively mode-locked solid-state laser using graphene oxide saturable absorber. The repetition rate of passively mode-locked pulse was 88 MHz with the pulse energy of 13.6 nJ.     

Millijoule intracavity OPO driven by a passively Q-switched Nd:YVO<Subscript>4</Subscript> laser with AlGaInAs quantum-well saturable absorber

We originally demonstrate the use of an AlGaInAs periodic quantum-well absorber to achieve a quasi-continuous-wave (QCW) diode-pumped passively Q-switched Nd:YVO₄ laser with an intracavity optical parametric oscillator (OPO). With a diode-pumping energy of 35 mJ, the output pulse energy and the pulse width at 1573 nm are found to be 1.58 mJ and 26 ns, respectively. The pulse repetition rate can be up to 100 Hz with the overall OPO beam quality M² factor to be better than 1.5.     

Comparative study of the mode-locking of Nd:GdVO_4 and Nd:YAG lasers with semiconductor saturable absorber mirrors

Stable continuous-wave passive mode-locking of diode-end-pumped Nd:GdVO4 and Nd:YAG lasers with semiconductor saturable absorber mirrors (SESAMs) are reported. The comparative study shows that the Nd:GdVO4 crystal is efficient to decrease the Q-switched mode-locking tendency, and easier to continuous-wave (CW) mode lock than Nd:YAG.     

Control of the pulse width in a diode-pumped passively Q-switched Nd:YVO<Subscript>4</Subscript>/KTP green laser with GaAs saturable absorber

By varying the positions of the saturable absorber in the laser axis and the pump beam waist in the gain medium, respectively, we have theoretically and experimentally studied the control of the pulse width in a diode-pumped passively Q-switched Nd:YVO₄/KTP green laser with GaAs saturable absorber. A rate equation model is introduced, in which the intracavity photon density is assumed to be Gaussian spatial distribution, the longitudinal variation of the intracavity photon density and the pump beam spatial distribution are also considered. The experimental results are consistent with the numerical calculations of the rate equations.     

High-pulse-stability double-end continuous-grown YVO<Subscript>4</Subscript>/Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript> acousto-optically Q-switched laser at high repetition rates

High pulse amplitude stability of 0.62% (rms) is achieved at 60 kHz repetition rate in fundamental mode with double-end continuous-grown YVO₄/Nd:YVO₄/YVO₄ composite crystal. The average output power and pulse peak power are 32.9 W and 27.7 kW, respectively, with 19.8 ns pulse width and 548 μJ pulse energy. The pulse amplitude stability is investigated experimentally. The stability gets improved with the decrease of repetition rate and output transmission. From theoretical analysis, the reason of pulse instability at high repetition rates is that the initial population inversion doesn’t saturate and the final population inversion doesn’t approach zero. With the decrease of repetition rate and output transmission, the final population inversion decreases and the interaction between two adjacent pulse periods is weakened. Therefore, pulse stability improves.     

880 nm LD pumped passive Q-switched and mode-locked Nd:YVO<Subscript>4</Subscript> laser using a single-walled carbon nanotube saturable absorber

We report a 880 nm LD pumped passive Q-switched and mode-locked Nd:YVO₄ laser using a single-walled carbon nanotube saturable absorber (SWCNT-SA). At the pump power of 7.78 W, the average out-put power of 330 mW of Q-switched and mode-locked laser with optical conversion efficiency of 4.2% was generated. The repetition rate and pulse width of the Q-switched envelope were 33 kHz and 5.6 μs, respectively. The repetition rate and pulse energy of the mode-locked pulse within the Q-switched envelope were 80 MHz and 4.1 nJ, respectively.     

37 W 888-nm-pumped grown-together composite crystal YVO<Subscript>4</Subscript>/Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript> oscillator at 1342 nm

We report on a continuous-wave Nd:YVO₄ oscillator at 1342 nm based on the combination of a grown-together composite crystal YVO₄/Nd:YVO₄/YVO₄ and the 888 nm diode-laser direct pumping for the first time. At the absorbed pump power of 102 W, a maximum average output power of 37.2 W at 1342 nm was obtained, corresponding to an optical-optical conversion efficiency of 36.5% and a high slope efficiency of 63.0%, respectively. To the best of our knowledge, this is the highest output power ever obtained for a 1342 nm Nd:YVO₄ oscillator.     

Stationary generation of diode-pumped self-Raman Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript> composite crystal laser

Output power dependences of composite Nd³⁺:YVO₄ Raman laser stationary generation on the longitudinal diode pump power are measured at different transmissions of the output mirror at the Stokes radiation frequency. The deviation of the measured dependences from linear is explained by the influence of thermal effects on both the overlap of the beams and diffraction losses. A method to estimate the laser and Stokes losses in the cavity and the parameters characterizing the overlap of the laser radiation with the pump and Stokes beams is proposed. A Stokes-component of power 2.1 W is obtained and corresponds to 12% diode-to-Stokes efficiency.     

Diode-pumped passively mode-locked Nd:GdVO<Subscript>4</Subscript> laser with a GaAs saturable absorber mirror

We report on a diode end-pumped passively mode-locked Nd:GdVO₄ laser. By using a GaAs wafer simultaneously as the saturable absorber and the output coupler, stable continuous-wave mode locking was achieved. The pulse width was measured to be 18.9 picoseconds at a repetition rate of 370 MHz. The most remarkable property of the laser is that its repetition rate can be changed from 370 MHz to 3.348 GHz by simply changing the cavity length. An average output power of 3.46 W at a 3.348 GHz repetition rate was obtained with a 14 W pump power. To our knowledge, this is the first demonstration of a passively mode-locked Nd:GdVO₄ laser using a GaAs wafer as the saturable absorber. PACS 42.55.Rz; 42.60.Fc; 42.55.Xi.     

Single-longitudinal mode Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript>/KTP green solid state laser

We present the concept and practical realization of a single frequency, tuneable diode pumped Nd:YVO₄/YVO₄/KTP microchip laser operating at 532 nm. Theoretical analysis of the single mode operation of such a laser configuration is presented. The single frequency operation has been obtained in a birefringent filter, where an YVO₄ beam displacer acts as an ideal polarizer. Experimental results are in good agreement with theoretical analysis. We have obtained stable single frequency operation, tuneable over 0.6 nm in the spectral range around 1064 nm. The laser operated with output power up to 110 mW at 53 nm. The total optical efficiency (808 nm to 532 nm) was 14%.     

Passively Q-switched yellow laser formed by a self-Raman composite Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript> crystal

Passively Q-switched yellow output from a frequency-doubled self-stimulating Raman composite Nd:YVO₄/YVO₄ laser using a Cr:YAG saturable absorber is reported. Maximum yellow output power of 264 mW was obtained with corresponding diode to yellow conversion efficiency of 5.9%.