Passively mode-locked high-power Nd:YAG lasers. with multiple laser heads

We discuss power scaling of passively mode-locked lasers using multiple laser heads in the resonator. We experimentally compared two different approaches for the cavity design, both using three side-pumped Nd:YAG laser heads. We obtained a record-high average output power of up to 27 W with close to diffraction-limited beam quality, a pulse duration of 19 ps, a pulse energy of 0.5 7J, and 23 kW peak power. Single-pass second-harmonic generation in a 10-mm-long LBO crystal yields 16.2 W of 532-nm radiation.     

High efficiency passive mode-locked Nd:YVO<Subscript>4</Subscript> laser based on SESAM under direct pumping at 880 nm

We report on an 880 nm LD pumped passive mode-locked TEM₀₀ Nd:YVO₄ laser based on a semiconductor saturable absorber mirror (SESAM), with a high optical-to-optical conversion efficiency of 67.3%, and a slope efficiency of 71%. When the absorbed pump power was 11 W, 7.4 W average output power of 1064 nm continuous-wave mode-locked laser was achieved. To our knowledge, this is the highest optical-to-optical conversion efficiency among all the published reports of 880 nm LD pumped SESAM passive mode-locked lasers. The repetition rate of mode-locked pulse was 80 MHz with 26 ps pulse width. The maximum pulse energy and peak power were 92.5 nJ and 3.6 kW, respectively.     

High Speed Demultiplexer Based on a Three-Wavelength SLA

By using a semiconductor laser amplifier (SLA) with a three-wavelength configuration, which works as a nonlinear element in an optical loop mirror, a demultiplexer device for ultra-fast processing is presented. The simulation shows that its switching time can be less than 10 ps at the holding beam power of 1 W, therefore it has the ability of demultiplexing one bit data from 100 Gb/s Optical Time Division Multiplexing (OTDM) pulse trains at the control power of 1 W.     

High Speed Demultiplexer Based on a Three-Wavelength SLA

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Passive picosecond and femtosecond mode-locking laser action of Yb<Superscript>3+</Superscript>:LuYSiO<Subscript>5</Subscript>

Efficient passive mode locking of a diode-pumped Yb³⁺:LuYSiO₅ (Yb:LYSO) laser is first demonstrated in experiment using a semiconductor saturable absorber mirror (SESAM), to the best of our knowledge. A stable pulse train with a repetition rate of 101 MHz is generated. The average output power of 2.13 W and the pulse duration of 3.9 ps. With a pair of SF10 uncoated prisms for dispersion compensation, we obtained pulses as short as 780 fs with center wavelength around 1042 nm, the average output power of 1.03 W and the peak power of 13.1 kW.     

Compact efficient self-frequency Raman conversion in diode-pumped passively Q-switched Nd:GdVO<Subscript>4</Subscript> laser

I report the first demonstration of the generation of efficient sub-nanosecond self-stimulated Raman pulses by a diode-pumped passively Q-switched Nd:GdVO₄/Cr⁴⁺:YAG laser. The conversion efficiency for the average power is 7% from pump diode input to self-Raman output and the slope efficiency is up to 14%. At an incident pump power of 2.0 W, the pulse duration, pulse energy, and peak power for the Stokes wavelength of 1175.6 nm were found to be 750 ps, 6.3 J, and 8.4 kW, respectively, with a pulse-repetition rate of 22 kHz. PACS 42.55.Ye; 42.55.Xi; 42.60.Gd     

Compact efficient diode-end-pumped intracavity frequency-tripled Nd:YVO<Subscript>4</Subscript> 355 nm laser

A compact efficient diode-end-pumped acousto-optically Q-switched intracavity-frequency-tripled Nd:YVO₄ 355 μm ultraviolet laser was realized. Intracavity sub-resonators with anti-reflection and high-reflection coated mirrors were used to get higher efficiency of third harmonic generation. With two LBO crystals used in frequency doubling and tripling processes, greater than 1.46 W 355 nm average output power was obtained under the absorbed pump power of 13.9 W and the repetition rate of 10 kHz. The corresponding pump-to-ultraviolet conversion efficiency was determined to be as high as 10.5%. At 10 kHz, the minimize pulse width was obtained to be 12 ns with the peak power of 10.4 kW and single pulse energy of 146 μJ.     

High peak power and sub-picosecond Fourier-limited pulse generation from passively mode-locked monolithic two-section gain-guided tapered InGaAs quantum-dot lasers

We report on the development of a new generation of high-power ultrashort pulse quantum-dot lasers with tapered gain section. Two device designs are proposed and fabricated, with different total lengths and absorber-to-gain-section length-ratios. These designs have been informed by numerical simulations of the dynamic mode-locking regimes and their dependence on the structural parameters. One device design demonstrated a record-high peak power of 17.7 W with 1.26 ps pulse width and a second design enabled the generation of a Fourier-limited 672 fs pulse width with a peak power of 3.8 W. A maximum output average power of 288 mW with 28.7 pJ pulse energy was also attained. In addition, the integrated timing jitter of 2.6 ps and far-field patterns are demonstrated.     

41 mW high average power picosecond 177.3 nm laser by second-harmonic generation in KBBF

We report on the generation of high average power, high repetition rate, and picosecond (ps) deep-ultraviolet (DUV) 177.3 nm laser. The DUV laser is produced by second-harmonic generation of a frequency-tripled mode-locked Nd: YVO₄ laser (<15 ps, 80 MHz) with KBBF nonlinear crystal. The influence of different fundamental beam diameters on DUV output power and KBBF-SHG conversion efficiency are investigated. Under the 355 nm pump power of 7.5 W with beam diameter of 145 μm, 41 mW DUV output at 177.3 nm is obtained. To our knowledge, this is the highest average power for the 177.3 nm laser. Our results provide a power scaling by three times with respect to previous best works.     

23W peak power picosecond pulses from a single-stage all-semiconductor master oscillator power amplifier

Using a single-stage all-semiconductor master oscillator-power amplifier, we generate narrow-band laser pulses of 23?W peak power at 1063?nm wavelength. These pulses of 40?ps length FWHM have a variable repetition rate and pulse energies around 2?nJ, which exceeds previous realizations and makes them ideally suited for second harmonic generation. With a spectral filter, an extinction ratio above 36?dB could be achieved at nearly 10?W peak power. We use a novel spectral method to reliably determine pulse energies independently of the background level.     

Diode-pumped passively mode-locked Yb:LSO/SESAM laser

Diode-end-pumped passively mode-locked Yb³⁺:Lu₂SiO₅ (Yb:LSO) lasers both in the picosecond and the femtosecond regimes were demonstrated in this paper. The mode-locked lasers were initiated by using of semiconductor saturable absorber mirrors (SESAM). In the absence of intra-prisms for pulse compression, the laser emitted 1.6 W of output power with pulses width of about 4.3 ps. A pair of SF10 prisms was inserted into the laser cavity, pulses as short as 699 fs was generated around a center wavelength of 1043.6 nm with an average output power of 800 mW and a peak power of 11.0 kW.     

Additive-pulse mode locking of a diode-pumped Nd3+:YVO4 laser

We demonstrate self-starting additive-pulse mode locking of a diode-pumped Nd³⁺:YVO₄ laser. Pulse durations of 2.7 ps are measured at a repetition frequency of 90.7 MHz and at an average output power of 1.1 W. This corresponds to a peak power of 4.5 kW. Received: 27 June 2001 / Revised version: 10 October 2001 / Published online: 29 November 2001     

High-peak-power second-harmonic generation of single-stage Yb-doped fiber amplifiers

A high-peak-power and high-repetition-rate fiber laser architecture is successfully demonstrated using a single-stage fiber amplifier. Nonlinear optical effects in a fiber amplifier degrade the monochromaticity of amplified laser pulses. In general, it is difficult for a non-monochromatic laser pulse to realize high-order harmonic generation with bulk nonlinear optical crystals. To overcome this problem, a single-stage amplifier architecture and a gain fiber with a high cladding absorption coefficient are employed. Furthermore, single-stage amplification enables the use of a multi-longitudinal mode electro-optically (EO) Q-switched micro seed laser. This architecture can generate a peak power of 100 kW at 50 kHz and an average power of 10 W. A second-harmonic conversion efficiency of 51% is obtained using this architecture and a LiB₃O₅ (LBO) crystal.     

Compact high conversion efficiency Nd:YAG/LBO green laser using unstable V cavity

We demonstrated a 36.9 W green laser with an intra-cavity second harmonic generation. A compact unstable V type cavity was adopted to compress the whole cavity configuration. The type I phase-matching LiB₃O₅ was used as the nonlinear crystal in the second harmonic generation. The 36.9 W average power and 38 ns pulse width of 532 nm green laser was obtained at a repetition rate of 10.3 kHz, corresponding to a peak power of 94 kW. The optical to optical conversion efficiency from diode to green and from IR to green laser was about 19.8 and 82%, the whole cavity length is about 300 mm. To the best of our knowledge, this is the shortest cavity configuration of side pump green system with output power higher than 30 W and IR to green conversion efficiency larger than 80%. The output fluctuation of this system was less than 3% in 2 h.     

Generation of 2.1 μm wavelength from degenerate high gray track resistant potassium titanyl phosphate optical parametric oscillator

This paper presents the experimental results of degenerate optical parametric generation using a high gray track resistant potassium titanyl phosphate (HGTR KTP) optical parametric oscillator (OPO). An average output power of 7 W at 10 kHz has been achieved that includes both signal and idler powers near degeneracy using 20 W average power from a 1064 nm Nd:YVO₄ pump source corresponding to an optical conversion efficiency of 35%.     

Efficient sub-nanosecond intracavity optical parametric oscillator pumped with a passively Q-switched Nd:GdVO<Subscript>4</Subscript> laser

An efficient diode-pumped passively Q-switched Nd:GdVO₄/Cr⁴⁺:YAG laser was employed to generate a high-repetition-rate, high-peak-power eye-safe laser beam with an intracavity optical parametric oscillator (OPO) based on a KTP crystal. The conversion efficiency for the average power is 8.3% from pump diode input to OPO signal output and the slope efficiency is up to 10%. At an incident pump power of 14.5 W, the compact intracavity OPO cavity, operating at 46 kHz, produces average powers at 1571 nm up to 1.2 W with a pulse width as short as 700 ps. PACS 42.60.Gd; 42.65.Yj; 42.55.X     

Passive mode-locking in diode-pumped c-cut Nd:LuVO<Subscript>4</Subscript> laser with a semiconductor saturable-absorber mirror

We demonstrated a diode-pumped passively mode-locked c-cut Nd:LuVO₄ picosecond laser with a semiconductor saturable-absorber mirror (SESAM) at a wavelength of 1067.8 nm. Due to the wide bandwidth of 0.48 nm, stable mode-locking has been generated with a duration as short as 3.7 ps, which is shorter than for the a-cut Nd:LuVO₄ laser. A maximum output power of 1.67 W was achieved to give a highest peak power of 3.47 KW at 18 W absorbed pump power.     

Design and simulation of an all-optical photonic crystal AND gate using nonlinear Kerr effect

A photonic crystal optical limiter with a sharp input-output characteristic curve is initially designed in this paper. Thereafter; using an optimized Y-junction, a new topology for an all-optical photonic crystal AND gate is proposed. The mentioned gate has a transition time less than 1?ps, a delay time less than 0.4?ps and occupies an area less than 100?μm². The 1,550?nm input lasers should have a power equal to 10W to be able to trigger the switching mechanism. The photonic crystal used for this purpose is a two dimensional triangular lattice of holes in a GaAs substrate. PWE and FDTD methods are used to simulate the proposed structure. Time domain simulations confirm the switching mechanism of the proposed AND gate.     

A comprehensive study of Nd:YAG,Nd:YAlO<Subscript>3</Subscript>, Nd:YVO<Subscript>4</Subscript> and Nd:YGdVO<Subscript>4</Subscript> lasers operating at wavelengths of 0.9 and 1.3 μm. Part 2: passively mode locked-operation

This paper reports on the generation of picosecond (ps) laser pulses by self-phase-adjusting additive-pulse-mode-locking (PSA) at wavelengths of 0.9 and 1.3 μm. The main objective of this work was to investigate and compare the characteristic optical properties of ps lasers based on different Nd-doped laser crystals like Nd:YAG, Nd:YAlO₃, Nd:YVO₄ and Nd:GdVO₄. As a result of these investigations a mode-locked Nd:YVO₄ laser for example, generated, ps pulses at 1.3 μm with a duration of 7 ps, a repetition rate of 160 MHz and an average power of 4.7 W. At 0.9 μm pulses with a duration of 1.9 ps were obtained at a repetition rate of 158 MHz and an average power of 2.8 W. PACS  42.70.Hj; 42.65.Re; 42.65.Ky     

888 nm pumped 1342 nm Nd:YVO<Subscript>4</Subscript> oscillator Kerr-lens mode-locked using cascaded second-order nonlinearities

We report on a parametric Kerr-lens mode-locked 888 nm pumped Nd:YVO₄ 1342 nm oscillator using cascaded second-order nonlinearities in LBO. Stable ps-pulse-operation was achieved. For an output coupling of T=25% high average output power of 6.5 W, emitting Fourier-limited pulses with a duration of 10 ps was reached. By changing the output coupling to T=10%, we achieved much shorter pulses with a pulse duration of 4 ps for less lower average power of 4.8 W. The beam was diffraction limited with an M ² parameter better than <1.05.