Mirror-dispersion-controlled sub-10-fs optical parametric amplifier in the visible

Pulses from an optical parametric amplifier in the visible are compressed to sub-10-fs duration by a delay line made exclusively from chirped dielectric mirrors. We employ what we believe are the first ultrabroadband visible chirped mirrors, which provide negative group-delay dispersion up to the blue-green spectral region. The setup is compact and reliable, and we used it to observe, for what is to our knowledge the first time in organic molecules, coherent oscillations with periods as short as 16 fs.     

Sub-8-fs pulses from an ultrabroadband optical parametric amplifier in the visible

Pulses with 180-THz bandwidth and 2-microJ energy were generated by a noncollinear optical parametric amplifier in the visible, pumped by the second harmonic of a Ti:sapphire laser. A portion of the amplified pulse spectrum was compressed to 7.2 fs by use of a thin prism sequence.     

Octave-spanning carrier-envelope phase stabilized visible pulse with sub-3-fs pulse duration

The visible second harmonic of the idler output from a noncollinear optical parametric amplifier was compressed using adaptive dispersion control with a deformable mirror. The amplifier was pumped by and seeded in the signal path by a common 400 nm second-harmonic pulse from a Ti:sapphire regenerative amplifier. Thus, both the idler output and the second harmonic of the idler were passively carrier-envelope phase stabilized. The shortest pulse duration achieved was below 3 fs.     

High-power parametric amplification of 11.8-fs laser pulses with carrier-envelope phase control

Phase-stable parametric chirped-pulse amplification of ultrashort pulses from a carrier-envelope phase-stabilized mode-locked Ti:sapphire oscillator (11.0 fs) to 0.25 mJ/pulse at 1 kHz is demonstrated. Compression with a grating compressor and a LCD shaper yields near-Fourier-limited 11.8-fs pulses with an energy of 0.12 mJ. The amplifier is pumped by 532-nm pulses from a synchronized mode-locked laser, Nd:YAG amplifier system. This approach is shown to be promising for the next generation of ultrafast amplifiers aimed at producing terawatt-level phase-controlled few-cycle laser pulses.     

AOPDF-shaped optical parametric amplifier output in the visible

Time shaping of ultra-short visible pulses has been performed using a specially designed acousto-optic programmable dispersive filter of 50% efficiency at the output of a two-stage non-collinear optical parametric amplifier. The set-up is compact and reliable. It provides a tunable shaped source in the visible with unique features: a 4-ps shaping window with preserved tunability over 500–650 nm, and pulses as short as 30 fs. Several-μJ output energy is easily obtained.     

Self-stabilization of the carrier-envelope phase of an optical parametric amplifier verified with a photonic crystal fiber

Experimental verification is given for self-stabilization of the carrier-envelope phase (CEP) of idler pulses from a noncollinear optical parametric amplifier. The verification is performed by spectral interference (SI) between an octave-broadened supercontinuum (SC) and its second harmonic. This SC is generated by nonlinear propagation of the second harmonic of the idler through a photonic crystal fiber (PCF). Although the modulational instability causes the intensity and CEP fluctuation and the amplified spontaneous emission noise in PCF degrades the visibility of SI, the CEP is verified to be stabilized.     

Sub-20-fs pulses tunable across the visible from a blue-pumped single-pass noncollinear parametric converter

Femtosecond pulses with center wavelengths between 470 and 750 nm are generated in a single-stage type I BBO optical parametric amplifier pumped by a frequency-doubled 1-kHz Ti:sapphire amplifier. A high-quality white-light continuum is used as the seed. Pulse durations as short as 16 fs and pulse energies of as much as 11 microJ are observed. The quantum efficiency is ~25% for both 7- and 40-microJ pump pulses. This unique combination of ultrashort pulse duration and high conversion is made possible by noncollinear phase matching that permits a sufficiently large amplification bandwidth. Simultaneously the group velocities of the signal and the idler are effectively matched. As a result widely tunable sub-20-fs pulses can be generated in a nonlinear crystal as thick as 2 mm.     

Dispersion management for a sub-10-fs, 10 TW optical parametric chirped-pulse amplifier

We report the amplification of three-cycle, 8.5 fs optical pulses in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) up to energies of 80 mJ. Improved dispersion management in the amplifier by means of a combination of reflection grisms and a chirped-mirror stretcher allowed us to recompress the amplified pulses to within 6% of their Fourier limit. The novel ultrabroad, ultraprecise dispersion control technology presented in this work opens the way to scaling multiterawatt technology to even shorter pulses by optimizing the OPCPA bandwidth.     

20-50-fs pulses tunable across the near infrared from a blue-pumped noncollinear parametric amplifier

A two-stage blue-pumped noncollinearly phase matched optical parametric amplifier was used to generate near-infrared pulses that were continuously tunable from 865 to 1600 nm. The pulse lengths scaled from 20 fs at the shorter wavelengths to below 50 fs at 1600 nm, with a nearly Fourier-transform-limited bandwidth. From 200 muJ of 775-nm pump light at a 1-kHz repetition rate and a 130-fs duration, 7-2.5-muJ pulse energies were generated, corresponding to a typical quantum efficiency of 25% from blue to near-infrared light.     

Pulse-front-matched optical parametric amplification for sub-10-fs pulse generation tunable in the visible and near infrared

A noncollinear optical parametric amplifier is presented that generates transform-limited sub-10-fs pulses that are tunable in both the visible and the near infrared (NIR). The pulse-front-matched pump geometry realizes tilt-free signal amplification, and pulses as short as 6.1 fs can be obtained from 550 to 700 nm. The large angular dispersion of the idler specific to the group-velocity-matching interaction is effectively eliminated by a grating-telescope compensator, and 9-fs NIR pulses are also successfully obtained from 900 to 1300 nm. This is believed to be the first tunable sub-10-fs light source.     

Generation of 14.8-fs pulses in a spatially dispersed amplifier

We demonstrate amplification and compression of 110-nm broad spectra in a spatially dispersed amplifier for what is believed to be the first time and generate 14.8-fs pulses with 450 microJ of energy at a repetition rate of 1 kHz. The amplifier concept is scalable in energy and allows for spectral shaping, which was demonstrated and compared with numerical simulations and showed excellent agreement.     

300 microJ noncollinear optical parametric amplifier in the visible at 1 kHz repetition rate

We demonstrate an order-of-magnitude energy scaling of a white-light seeded noncollinear optical parametric amplifier in the visible. The generated pulses, tunable between 520 and 650 nm with sub-25-fs duration, had energies up to 310 microJ with 20% blue-pump-to-signal energy conversion efficiency at 540 nm. This new ultrafast source will make possible numerous extreme nonlinear optics applications. As a first application, we demonstrate the generation of tunable vacuum ultraviolet pulses.     

Efficient visible femtosecond optical parametric generator and amplifier using tilted pulse-front pumping

Using pulses with tilted pulse fronts to compensate for the group-velocity mismatch in three-wave interactions, we constructed an efficient 400-nm pumped femtosecond collinear typeI phase-matched beta -barium borate optical parametric generator and amplifier. The signal and idler outputs are tunable from 470nm to 2.7 microm and have pulse widths in the range of 100170fs at a 1-kHz repetition rate. A maximum output energy of 6.5 microJ and a total conversion efficiency of more than 15% were achieved.     

Determining the carrier-envelope offset frequency of 5-fs pulses with extreme nonlinear optics in ZnO

We excite ZnO samples with two-cycle optical pulses directly from a mode-locked oscillator with average powers of several tens of milliwatts. The emitted light reveals peaks at the carrier-envelope offset frequency f(?) and at 2f(?) in the radio-frequency spectra. These peaks can still be detected in layers as thin as 350 nm-a step toward determining the carrier-envelope offset phase itself.     

Long-term carrier-envelope phase stability from a grating-based, chirped pulse amplifier

We demonstrate a carrier-envelope phase (CEP) stabilized, chirped pulse laser amplifier that exhibits greatly improved intrinsic long-term CEP stability compared with that of other amplifiers. This system employs a grating-based stretcher and compressor and a cryogenically cooled laser amplifier. Single-shot carrier envelope phase noise measurements are also presented that avoid underestimation of this parameter caused by fringe averaging and represent a rigorously accurate upper limit on CEP noise.     

Programmable dispersion compensation and pulse shaping in a 26-fs chirped-pulse amplifier

We have constructed a 26-fs chirped-pulse amplifier that incorporates a programmable liquid-crystal spatial light modulator in the pulse stretcher. The modulator serves a dual purpose. First, we apply frequency-dependent phase shifts to compensate for cubic, quartic, and nonlinear phase dispersion in the amplifier, which results in a reduction in pulse duration from 32 to 26 fs, in agreement with the transform limit of the amplified pulse spectrum. Second, we are able to produce high-fidelity compressed amplified shaped pulses by applying phase masks directly within the stretcher. Shaped pulse energies of greater than 1 mJ are routinely obtained.     

Sub-20 fs visible pulses with 750 nJ energy from a 100 kHz noncollinear optical parametric amplifier

We demonstrate the operation of a 100 kHz noncollinear optical parametric amplifier that is pumped by just a few microjoules of 800 nm pulses with 50 fs duration. The device delivers sub-20 fs pulses tunable from 460 nm to beyond 1 microm and pulse energies up to 750 nJ when it is pumped with 7 microJ of energy. The design of the single-stage amplifier has been carefully optimized, and the design considerations are discussed.     

Mirror-dispersion-controlled OPA: a compact tool for sub-10-fs spectroscopy in the visible

We report on a sub-10-fs optical parametric amplifier in the visible, using noncollinear phase matching in #-barium borate, with a pulse compressor made exclusively of chirped dielectric mirrors. We employ mirrors of novel design, providing negative group delay dispersion for bandwidths of over 200 THz, up to the blue-green spectral region. The resulting setup, compact, easy to operate and reliable, is an ideal tool for ultrafast spectroscopy with extremely high time resolution. We use these pulses to observe in the time domain coherent oscillations in organic molecules with period as short as 16 fs.