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We demonstrate the generation of sub-two-cycle intense laser pulses based on two-stage hollow-core fiber (HCF) compression in a compact setup (footprint of 0.65 m × 2.85 m) using a commercial Yb:KGW regenerative amplifier. Spectrally broadened laser pulses with an output power of 7.2 W from the second HCF stage are compressed down to 6.6 fs (1.9 cycles at 1030 nm) using a pair of chirp mirrors and a pair of wedges with an efficiency of 86%, leading to a compressed output of 6.2 W. A pulse-to-pulse energy stability of 0.17% is measured for 10 min.

We firstly report a 2-µm all-fiber nonlinear pulse compressor based on two pieces of normal dispersion fiber (NDF), which enables a high-power scaling ability of watt-level and a high pulse compression ratio of 13.7. With the NDF-based all-fiber nonlinear pulse compressor, the 450-fs laser pulses with a repetition rate of 101.4 MHz are compressed to 35.1 fs, corresponding to a 5.2 optical oscillation cycle at the 2-µm wavelength region. The output average power reaches 1.28 W, which is believed to be the highest value never achieved from the previous 2-µm all-fiber nonlinear pulse compressors with a high pulse repetition rate above 100 MHz. The dynamic evolution of the ultrafast pulse inside the all-fiber nonlinear pulse compressor is numerically analyzed, matching well with the experimental results. [ABSTRACT FROM AUTHOR]

In this work, we present a high-power, high-repetition-rate, all-fiber femtosecond laser system operating at 1.5 µm. This all-fiber laser system can deliver femtosecond pulses at a fundamental repetition rate of 10.6 GHz with an average output power of 106.4 W -- the highest average power reported so far from an all-fiber femtosecond laser at 1.5 µm, to the best of our knowledge. By utilizing the soliton-effect-based pulse compression effect with optimized pre-chirping dispersion, the amplified pulses are compressed to 239 fs in an all-fiber configuration. Empowered by such a high-power ultrafast fiber laser system, we further explore the nonlinear interaction among transverse modes LP01, LP11 and LP21 that are expected to potentially exist in fiber laser systems using large-mode-area fibers. The intermodal modulational instability is theoretically investigated and subsequently identified in our experiments. Such a high-power all-fiber ultrafast laser without bulky free-space optics is anticipated to be a promising laser source for applications that specifically require compact and robust operation. [ABSTRACT FROM AUTHOR]

When an ultrafast optical pulse with high intensity propagates through transparent material a supercontinuum can be coherently generated by self‐phase modulation, which is essential to many photonic applications in fibers and integrated waveguides. However, the presence of dispersion causes stagnation of spectral broadening past a certain propagation length, requiring an increased input peak power for further broadening. Overcoming such spectral stagnation will be key to achieve practical integrated supercontinuum devices. Here, a concept is presented to drive supercontinuum generation with significantly lower input power by counteracting spectral stagnation via repeatedly alternating the sign of group velocity dispersion along the propagation. The effect is experimentally demonstrated in dispersion alternating fiber in excellent agreement with modeling, revealing almost an order of magnitude reduced peak power compared to uniform dispersion. Calculations also reveal a similar power reduction with integrated optical waveguides, simultaneously with a significant increase in flat bandwidth, which is important for on‐chip broadband photonics. [ABSTRACT FROM AUTHOR]

We show theoretically and numerically how to optimize sign-alternating dispersion waveguides for maximum nonlinear pulse compression, while leveraging the substantial increase in bandwidth-to-input peak power advantage of these structures. We find that the spectral phase can converge to a parabolic profile independent of uncompensated higher-order dispersion. The combination of an easy to compress phase spectrum, with low input power requirements, then makes sign-alternating dispersion a scheme for high-quality nonlinear pulse compression that does not require high powered lasers, which is beneficial for instance in integrated photonic circuits. We also show a new nonlinear compression regime and soliton shaping dynamic only seen in sign-alternating dispersion waveguides. Through an example SiN-based integrated waveguide, we show that the dynamic enables the attainment of compression to two optical cycles at a pulse energy of 100 pJ which surpasses the compression achieved using similar parameters for a current state-of-the-art SiN system.

We demonstrate a self-seeded multicasting device capable of delivering a large number of signal integrity preserving spectrally-distinct copies. The new multicasting device relies on efficient higher-order mixing in a two-pump parametric mixer. Precise dispersion engineering was deployed to generate a frequency-comb spanning over a 140-nm band, and resulted in the creation of more than 60 spectral copies of the signal with conversion efficiencies higher than -3 dB. The fidelity of the multicasting device with respect to signal intensity and phase was characterized experimentally. The spectral replication process was found to induce low penalty with both ON-OFF and differential phase-shift keying signals, thereby indicating compatibility with arbitrary amplitude/phase signaling formats. [ABSTRACT FROM PUBLISHER]

We investigate numerically the second-harmonic generation from near infrared 100 fs pulses in periodically and aperiodically poled lithium niobate crystals, taking into account the group-velocity mismatch, the group-velocity dispersion, and self-action effects. For the first time, we show that a tenfold pulse compression can be obtained at both fundamental and second-harmonic frequencies. The mechanism of compression and the pertinent quality factors are discussed. [ABSTRACT FROM AUTHOR]

We show theoretically and numerically how to optimize sign-alternating dispersion waveguides for maximum nonlinear pulse compression, while leveraging the substantial increase in bandwidth-to-input peak power advantage of these structures. We find that the spectral phase can converge to a parabolic profile independent of uncompensated higher-order dispersion. The combination of an easy to compress phase spectrum, with low input power requirements, then makes sign-alternating dispersion a scheme for high-quality nonlinear pulse compression that does not require high powered lasers, which is beneficial for instance in integrated photonic circuits. We also show a new nonlinear compression regime and soliton shaping dynamic only seen in sign-alternating dispersion waveguides. Through an example SiN-based integrated waveguide, we show that the dynamic enables the attainment of compression to two optical cycles at a pulse energy of 100 pJ which surpasses the compression achieved using similar parameters for a current state-of-the-art SiN system. [ABSTRACT FROM AUTHOR]

We present a dual semiconductor laser system at 1.55 mum with femtosecond pulse widths and very low timing jitter for rapid pump-probe measurements. Synchronizing the two lasers to the same low-noise radio frequency-oscillator allows the use of an electrical phase shifter for the relative time delay between the lasers. This leads to a large scanning window that nearly matches the pulse period of 2.5 ns, as well as achieving a discrete time step of below 100 fs. The timing jitter of the complete dual laser system including all electronics is only 540 fs across the whole time delay. The nonlinear pulse compression using especially designed comb-like dispersion profiled fiber leads to autocorrelation widths of 310 fs. The system performance, i.e., the high time resolution is demonstrated by optical cross correlation of the pump and probe pulse, showing a very low full-width at half maximum of 1.3 ps [ABSTRACT FROM PUBLISHER]