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.     

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.     

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.     

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%.     

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.     

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.     

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.     

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%.     

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.     

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.     

Passively Q-switched intracavity frequency-doubled Nd:LuVO<Subscript>4</Subscript>/LBO green laser with a Cr<Superscript>4+</Superscript>:YAG saturable absorber

This work presents experimental results concerning a passively Q-switched intracavity frequencydoubled Nd:LuVO₄/LBO green laser with a Cr⁴⁺:YAG saturable absorber operated at the wavelength of 0.53 μm. A maximal output power of 1.28 W was obtained at a pump power of 16.34 W, and peak power, pulse width as well as repetition frequency were 1.48 kW, 41 ns and 21 kHz, respectively.     

High power ultrafast Nd:YVO<Subscript>4</Subscript> laser mode locked by single wall carbon nanotube absorber

We use a single walled carbon nanotubes (SWCNTs) absorber to demonstrate a high power mode locking for Nd:YVO₄ lasers. Under the pump power of 12 W, continuous wave mode-locked (CWML) pulse were generated with the maximum average output power of 3.6 W and the pulse duration of 7.6 ps. The peak power and the single pulse energy of the mode-locked laser were up to 4.9 kW and 37.5 nJ, respectively. To our knowledge, this is the highest average output power of the CWML laser with the SWCNTs absorber reported.     

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.     

High-peak-power diode-pumped passively Q-switched Nd:YVO<Subscript>4</Subscript> laser

We report on a passively Q-switched diode-pumped Nd:YVO₄ laser polarized along the a axis (corresponding to the smallest value of emission cross section at 1064 nm), generating 157-μJ pulses with 6.0-ns time duration (>20 kW peak power) and 3.6 W of average power at 1064 nm with good beam quality (M²<1.4). The selection of the polarization was performed by a novel technique relying on the birefringence of the laser crystal and on the misalignment sensitivity of the resonator. Received: 30 September 2002 / Revised version: 22 November 2002 / Published online: 19 March 2003 RID="*" ID="*"Corresponding author. Fax: +39-382/422583, E-mail: agnesi@ele.unipv.it     

LD end-pumped passively mode-locked Nd:YVO<Subscript>4</Subscript> laser with single-walled carbon nanotubes

We demonstrate a LD end-pumped passively mode-locked Nd:YVO₄ laser using a single-walled carbon nanotubes saturable absorber (SWCNT-SA). The SWCNT wafer was fabricated by electric arc discharge method on quartz substrate with absorption wavelength of 1064 nm. At the absorbed pump of 15.8 W, an output power of 750 mW CW (continuous wave) mode-locked laser pulse was achieved with the repetition of 79.7 MHz, corresponding to optical-optical efficiency of 4.75%.     

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.     

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.     

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.     

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.     

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