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1.
Opt Lett ; 48(22): 6008-6011, 2023 Nov 15.
Article in English | MEDLINE | ID: mdl-37966775

ABSTRACT

We report on efficient single-pass optical parametric generation (OPG) of broadband femtosecond pulses in the mid-infrared at 10 MHz by exploiting group-velocity-matched interaction in a 42-mm-long MgO:PPLN crystal. Using a microchip-started femtosecond amplified Mamyshev oscillator at 1064 nm as the pump, the OPG source can provide tunable femtosecond pulses across 1516-1566 nm in the signal and 3318-3568 nm in the idler, with slope efficiencies of ∼93% and ∼41%, respectively. For 650 mW of average input pump power, signal powers of up to 283 mW at 1524 nm are generated, with more than 200 mW over the entire tuning range. Idler average powers of up to 104 mW at 3450 nm, with more than 80 mW across the full range, are also obtained. For input pump pulses of ∼182 fs, the generated signal pulses have a duration of ∼460 fs at 1516 nm. The idler pulses have a typical bandwidth of ≥100 nm over the entire tuning range, and as wide as 181 nm at 3457 nm. The OPG source exhibits excellent passive power stability, better than 0.5% rms in the signal and 0.6% rms in the idler, over 1 h, both in Gaussian TEM00 spatial profile with M2 < 1.5.

2.
Opt Lett ; 41(15): 3395-8, 2016 Aug 01.
Article in English | MEDLINE | ID: mdl-27472577

ABSTRACT

We report on a femtosecond high-power regenerative amplifier based on Yb:Lu2O3. Exploiting the excellent thermo-mechanical properties of this material, we were able to achieve up to 64.5 W in continuous-wave regime, limited only by the available pump power. In pulsed operation, 42 W of average output power at a repetition rate of 500 kHz with 780 fs long pulses could be demonstrated, resulting in a pulse peak power of ∼100 MW. The spectrum was centered at 1034 nm with an FWHM of 2.4 nm, potentially allowing for even shorter pulses. At the maximum output power the beam was nearly TEM00, with an M2 value of 1.2 in both axes.

3.
Opt Lett ; 40(7): 1532-5, 2015 Apr 01.
Article in English | MEDLINE | ID: mdl-25831377

ABSTRACT

We report for the first time, to the best of our knowledge, an innovative design concept for intracavity pulse stretching in a regenerative amplifier, employing a single "grating-mirror" based on a leaky-mode grating-waveguide design. The very compact and flexible layout allows for femtosecond pulses to be in principle easily stretched up to nanosecond durations. The design has been tested in a diode-pumped Yb:CALGO regenerative amplifier followed by a standard transmission grating compressor. Sub-200-fs pulses (stretched pulses ≈110 ps) with 205-µJ energy at 20-kHz repetition rate have been demonstrated. In order to prove the robustness and potential for energy scaling of leaky-mode grating-waveguide intracavity stretcher, we generated stretched pulses with energies of up to ≈700 µJ (400-ps long) at a lower repetition rate of 10 kHz. A simple model is proposed for the study of the cavity in presence of induced spatial chirp.

4.
Opt Express ; 22(17): 19912-8, 2014 Aug 25.
Article in English | MEDLINE | ID: mdl-25321201

ABSTRACT

We investigated and compared Yb:CaAlGdO4 and Yb:CaF2 regenerative amplifiers at repetition rates 5-10 kHz, a frequency range interesting for industrial applications requiring relatively high pulse energy. Both materials allow for pulse energies close to 1 mJ with sub-400-fs pulses. The two laser materials offer comparable performance in the pump power range investigated. The same regenerative amplifiers can be run up to 500 kHz for much faster material processing, with maximum output power of up to 9.4 W.

5.
Opt Lett ; 38(20): 4131-3, 2013 Oct 15.
Article in English | MEDLINE | ID: mdl-24321941

ABSTRACT

A new high-performance Yb:CaAlGdO(4) (Yb:CALGO) regenerative amplifier is demonstrated. Pumped by 116 W at ≈980 nm and seeded by means of a 92 fs oscillator, it generates as much as 36 W of average output power with chirped pulses, and 28 W with 217 fs compressed pulses at 500 kHz repetition rate. This corresponds to 56 µJ of pulse energy and 258 MW peak power. The compressed pulses have a time-bandwidth product of 0.69 and could be shortened further with an improved compressor setup.


Subject(s)
Lasers, Solid-State , Time Factors
6.
Rev Sci Instrum ; 82(11): 115107, 2011 Nov.
Article in English | MEDLINE | ID: mdl-22129013

ABSTRACT

We describe recent improvements in the development of the high power laser system used in the motion induced radiation (MIR) experiment to amplify electromagnetic fields inside a microwave cavity. The improvements made on the oscillator stabilization, the pulse train shaping device, and the spatial beam uniformity are reported.

7.
Opt Express ; 19(21): 20316-21, 2011 Oct 10.
Article in English | MEDLINE | ID: mdl-21997042

ABSTRACT

Pulse-picking from a 100-mW cw mode-locked seeder, a hybrid master-oscillator power-amplifier (MOPA) system, based on Nd:YVO4 and Nd:YAG amplifier modules, has been developed, delivering single-pulses of 8.6 ps at 455-MHz repetition-rate, bunched into ~1-µs trains of 50 mJ ("macro-pulses"). The output beam is linearly polarized and nearly diffraction limited up to the maximum macro-pulse repetition-rate of 50 Hz. The single-pulse peak power and the macro-pulse duration and energy are quite suitable for high-energy nonlinear optical applications such as low-threshold synchronously-pumped parametric converters in the mid infrared. The impact on the overall efficiency of saturation distortion of the macro-pulse envelope as well as of amplified spontaneous emission (ASE) is considered. The managing of the envelope distortion compensation and of the ASE suppression by means of fast saturable absorbers is reported.

8.
Opt Lett ; 36(16): 3236-8, 2011 Aug 15.
Article in English | MEDLINE | ID: mdl-21847219

ABSTRACT

We report a compact, efficient, high-energy, and high-repetition-rate mid-IR picosecond optical parametric oscillator (OPO) based on the new nonlinear material CdSiP(2) (CSP). The OPO is synchronously pumped by a master oscillator power amplifier system at 1064.1 nm, providing 1 µs long macropulses constituting 8.6 ps micropulses at 450 MHz, and it can be tuned over 486 nm across 6091-6577 nm, covering the technologically important wavelength range for surgical applications. Using a compact (∼30 cm) cavity and improved, high-quality nonlinear crystal, idler macropulse energy as high as 1.5 mJ has been obtained at 6275 nm at a photon conversion efficiency of 29.5%, with >1.2 mJ over more than 68% of the tuning range, for an input macropulse energy of 30 mJ. Both the signal and idler beams are recorded to have good beam quality with a Gaussian spatial profile, and the extracted signal pulses are measured to have durations of 10.6 ps. Further, from the experimentally measured transmission data at 1064 nm, we have estimated the two-photon absorption coefficient of CSP to be ß=2.4 cm/GW, with a corresponding energy bandgap, E(g)=2.08 eV.


Subject(s)
Cadmium Compounds/chemistry , Optical Phenomena , Phosphorus Compounds/chemistry , Silicon Compounds/chemistry , Infrared Rays
9.
Appl Opt ; 37(18): 3984-6, 1998 Jun 20.
Article in English | MEDLINE | ID: mdl-18273367

ABSTRACT

A diode-pumped Q-switched Nd:YAG laser that operates at the eye-safe 1444 nm wavelength has been developed. When pumped by a 10-W fiber-coupled array at 808 nm, it generated 1 W in cw operation and 560 mW at 20-kHz repetition rate with active Q-switching. Design issues such as thermal lensing characterization and beam quality are discussed.

10.
Appl Opt ; 36(3): 597-601, 1997 Jan 20.
Article in English | MEDLINE | ID: mdl-18250713

ABSTRACT

We report on the experimental results of a diode-pumped, intracavity-doubled cw Nd:YAG laser, pumped by a 10-W fiber-coupled semiconductor laser at 808 nm and emitting as much as 600 mW in a stable single longitudinal mode and TEM(00) spatial mode. We discuss the main issues of the resonator design and the optimization of the intracavity second harmonic conversion by interpreting our results using simple models. Improvements for the current project are also discussed.

11.
Opt Lett ; 22(18): 1415-7, 1997 Sep 15.
Article in English | MEDLINE | ID: mdl-18188255

ABSTRACT

A quasi-cw diode-pumped Nd:YAG laser, mode locked by a nonlinear mirror and stabilized by an acousto-optic modulator, has been developed that generates 31-ps, 23-microJ pulses. Employing this source with a periodically poled lithium niobate crystal in a traveling-wave geometry, we obtained extracavity frequency conversion with pump depletion of as much as 62% in the near infrared (1.46- 1.56 microm) with a pulse spectral width of 1.5nm and a beam quality M(2)=1.7.

12.
Opt Lett ; 22(21): 1645-7, 1997 Nov 01.
Article in English | MEDLINE | ID: mdl-18188324

ABSTRACT

A diode-pumped Nd(3+):YVO(4) laser passively mode locked by a nonlinear mirror based on second-harmonic generation has been developed. Pumping with a fiber-coupled 10-W diode array, we generated nearly diffraction limited, linearly polarized 11-ps pulses at 1064nm, with average power of 2.7 W at a 150-MHz repetition rate. Pulses as short as 7.9 ps were measured with reduced output power (1.35 W) by optimal focusing in the nonlinear crystal.

13.
Opt Lett ; 19(5): 359, 1994 Mar 01.
Article in English | MEDLINE | ID: mdl-19829642
14.
Opt Lett ; 18(8): 637, 1993 Apr 15.
Article in English | MEDLINE | ID: mdl-19802225
15.
Opt Lett ; 18(9): 717-9, 1993 May 01.
Article in English | MEDLINE | ID: mdl-19802250

ABSTRACT

We present a novel interpretation of Kerr lens mode locking based on the Z-scan operating principle and derive a few practical criteria for application to mode-locked solid-state laser systems.

16.
Opt Lett ; 17(24): 1764-6, 1992 Dec 15.
Article in English | MEDLINE | ID: mdl-19798309

ABSTRACT

A novel method for measuring the beam quality of short, powerful laser pulses is presented. The method is based on the Z-scan technique used to investigate the nonlinear susceptibilities of optical materials. It is shown that both two-photon absorption and nonlinear refraction of a nonlinear sample can be used to obtain information about the spatial quality of the pulses.

17.
Ann Rheum Dis ; 44(7): 455-61, 1985 Jul.
Article in English | MEDLINE | ID: mdl-4026406

ABSTRACT

Lung function was assessed in 20 patients with primary Sjögren's syndrome (SS) and in a group of patients with SS associated with a variety of connective tissue diseases. Signs of small airway disease and of altered diffusion capacity, together with chest x-ray features of mild interstitial involvement, were the most common findings in primary SS. On the whole, lung involvement was more frequent and severe in patients with the secondary form of the syndrome. In both primary and secondary SS lung function changes did not correlate with the other clinical and serological parameters, except for a more severe impairment of diffusion capacity in patients with Raynaud's phenomenon.


Subject(s)
Lung/physiopathology , Sjogren's Syndrome/physiopathology , Adult , Aged , Arthritis, Rheumatoid/complications , Cryoglobulinemia/complications , Female , Humans , Lupus Erythematosus, Systemic/complications , Middle Aged , Mixed Connective Tissue Disease/complications , Radiography , Respiratory Function Tests , Scleroderma, Systemic/complications , Sjogren's Syndrome/blood , Sjogren's Syndrome/complications , Sjogren's Syndrome/diagnostic imaging
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