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This Conference Presentation, “Boosting single-shot ultrafast imaging to 70 trillion frames per second and 1000 frames,” was recorded for the Photonics West 2021 Digital Forum.

We generalize the well-known method of generating nondiffracting beams based on axicons in the near-field using phase modulations with azimuthal dependencies. The enormous benefit of our concept for efficient shaping of nondiffracting beams with arbitrary transverse profiles is shown and optimized processes like cleaving of particularly thin and thick glasses using elliptical Bessel-like beams are discussed.

We demonstrate a novel algorithmic approach for second-harmonic-generation (SHG) frequency-resolved optical gating (FROG) that always converges and is also faster for complex pulses. It takes advantage of the Paley-Weiner Theorem for generating significantly better initial guesses. It also uses a multi-grid approach, which allows the algorithm to operate initially on smaller arrays for early iterations and only on the complete array for the final few iterations. We tested it on sets of twenty thousand noisy FROG traces and have achieved 100% convergence even for pulses with time-bandwidth products of 100.

Two-dimensional materials have attracted significant interest recently for their unique optical properties compared to their bulk counterparts. Specifically, the family of transition metal dichalcogenides (TMD), such as MoS2 and WS2, have large second order nonlinear susceptibility. Extraordinary second harmonic generation and sum frequency generation have been observed. Here we investigate the second order nonlinearity of 2D materials, including TMD layered materials with dopants and defects. Experimental results and preliminary theoretical analysis will be discussed.

We demonstrate three microfluidic chip based microfiber/nanofiber sensors for ultra-sensitive absorption, fluorescence, and femtoliter-scale sensing, respectively. The sensors shown here may open up new opportunities for ultra-sensitive biosensing and single molecule analysis.

A diagnostic method is presented that enables single shot characterization in amplitude and phase of ultrashort, weak pulses. The method is particularly well adapted to the characterization of pulses generated by optical parametric oscillators.

The present contribution is addressed to an improved method to fabricate dielectric dispersive compensating mirrors (CMs) with an increased laser induced damage threshold (LIDT) by the use of ternary composite layers. Taking advantage of a novel in-situ phase monitor system, it is possible to control the sensitive deposition process more precisely. The study is initiated by a design synthesis, to achieve optimum reflection and GDD values for a conventional high low stack (HL)n. Afterwards the field intensity is analyzed, and layers affected by highest electric field intensities are exchanged by ternary composites of TaxSiyOz. Both designs have similar target specifications whereby one design is using ternary composites and the other one is distinguished by a (HL)n. The first layers of the stack are switched applying in-situ optical broad band monitoring in conjunction with a forward re-optimization algorithm, which also manipulates the layers remaining for deposition at each switching event. To accomplish the demanded GDD-spectra, the last layers are controlled by a novel in-situ white light interferometer operating in the infrared spectral range. Finally the CMs are measured in a 10.000 on 1 procedure according to ISO 21254 applying pulses with a duration of 130 fs at a central wavelength of 775 nm to determine the laser induced damage threshold. © 2016 SPIE. Downloading of the abstract is permitted for personal use only. DFG/EXC/QUEST Volkswagen Stiftung BMBF/13N11558

Ultrafast imaging has been a key enabler to many novel imaging modalities, including looking behind corners and imaging behind scattering layers. With picosecond time resolution and unconventional sensing geometries, ultrafast imaging can fundamentally impact sensing capabilities in industrial and biomedical applications. This paper reviews the fundamentals, recent advances, and the future prospects of ultrafast imaging-based modalities.

A basic recipe for spatial shaping of spectrally and temporally partially coherent broadband pulsed fields like supercontinuum pulses is discussed. To shape these pulsed beams from Gaussian to flat-top shape, a shaping element is designed using the optical map transform method. The spatial profiles show a high quality flat-top region and the time integrated intensity profile is also of high quality flat-top shape. The spatiotemporal target field distribution is shown to bend, which is of practical importance in time-resolved experiments in ultrafast optics.

We use a continuous-wave low power incoherent seed to control spontaneous modulation instability (MI) in a highly-nonlinear optical fiber. We show both experimentally and numerically that spectral and noise properties of MI can be accurately controlled provided the spectral characteristics of the seed are chosen carefully. Specifically, we evidence the strong influence of the seed coherence on the output pulses signal-to-noise ratio and bandwidth. Stochastic nonlinear Schrodinger equation simulations are in excellent agreement with experiments.

The ELI-beamlines project is expected to reach state of the art parameters in its laser systems. The Laser Induced Damage Threshold of the corresponding optical systems will have to sustain the expected fluences and repetition rates. The LIDT requirements for the ultrafast pulse compressors, vacuum transport mirrors and high average power optics are presented together with the current and planned capabilities for LIDT testing with a 25 TW laser system at 800 and 1060 nm .

We demonstrate three-dimensional Airy-Bessel optical wave packets that propagate without broadening in time or space. We also demonstrate the non-dispersive and the self-healing nature of the Airy pulse. Since the propagation of an Airy- Bessel wave packet does not critically depend on the material properties, we believe the Airy-Bessel wave packet will find its usage in applications as practical devices.

We present apodised Bragg waveguides inscribed in fused silica using a high repetition rate fs laser system. By varying the modulation with a pulse picker, the mean refractive index over the grating length could be kept constant, while the grating strength is varied. Thus, Bragg waveguides with zero crossing Gaussian modulation profile could be demonstrated. The side-lobes were suppressed by about 10 dB compared to a uniform grating.

We report on the fabrication of birefringent optical components based on so-called nanogratings. These selforganized nanostructures with sub-wavelength periodicity are formed during femtosecond laser processing of transparent materials, resulting in characteristic birefringent modifications. Nanogratings provide the means for the direct inscription of customized birefringent elements with position-dependent retardation. We present our investigations on the formation process of nanogratings in fused silica and the influence of fabrication parameters, thereby identifying ways to systematically control the structural properties of the gratings. Consequently, we were able to fabricate nanograting-based birefringent elements with specific retardations in bulk fused silica.

Therapeutic treatment of spinal cord injuries, brain trauma, stroke, and neurodegenerative diseases will greatly benefit from the discovery of compounds that enhance neuronal regeneration following injury. We previously demonstrated the use of femtosecond laser microsurgery to induce precise and reproducible neural injury in C. elegans, and have developed microfluidic on-chip technologies that allow automated and rapid manipulation, orientation, and non-invasive immobilization of animals for sub-cellular resolution two-photon imaging and femtosecond-laser nanosurgery. These technologies include microfluidic whole-animal sorters, as well as integrated chips containing multiple addressable incubation chambers for exposure of individual animals to compounds and sub-cellular time-lapse imaging of hundreds of animals on a single chip. Our technologies can be used for a variety of highly sophisticated in vivo high-throughput compound and genetic screens, and we performed the first in vivo screen in C. elegans for compounds enhancing neuronal regrowth following femtosecond microsurgery. The compounds identified interact with a wide variety of cellular targets, such as cytoskeletal components, vesicle trafficking, and protein kinases that enhance neuronal regeneration.

We report the programmable pulse shaping of ultrabroadband pulses by the use of a novel design of electrostatic deformable mirror based on push pull technology. We achieved the formation of double and triple pulses with programmable delay and a pulse length of 20fs@1.3μm with spectrum tunability.

Laser microsintering of tungsten powder is investigated as a function of laser output power, pulse interval and vacuum level. The intensities are calculated for the evaporation thresholds of tungsten powder particles of various sizes. In addition, the powder layer generation and the resulting layer thicknesses are calculated. The powder abrasion occurring during the process was taken into consideration. Polished sections and REM images were prepared in order to analyse the experimental outcomes. The dependence of sinter density on the parameters is discussed.

Digital holography (DH) technique allows obtaining quantitative amplitude- and phase-contrast images. However, there are only several attempts to use advantages of digital holography in time resolved manner. Herewith we demonstrate that combination of conventional off-axis DH and ultrashort probing laser pulses results in versatile tool suitable for ultra-fast phenomena studies. We demonstrate its applications in spatial-temporal characterization of ionizing pre-damage propagation of femtosecond pulses in transparent material as well as characterization of post-damage ablation processes in metals. Phase-and amplitude-contrast images are obtained in single-shot mode with the best to our knowledge temporal resolution of ≈ 30 fs.

The fundamental difficulty of achieving a coherently enhanced sensing method at standoff distances greater than 10 meters has been solved by single-beam coherent anti-Stokes Raman scattering and by actively measuring and eliminating chromatic dispersion experienced by the broad-bandwidth (100 nm) laser pulses. Characteristic Raman spectra for several chemicals in gas, liquid, and solid states, are successfully obtained from a 12 meter standoff distance. The results obtained indicate this is a promising approach to standoff detection of chemicals, hazardous contaminations, and explosives.

In this work, spot-size dependence of surface femtosecond laser-induced damage threshold in fused silica is put in evidence when the damage reach the micrometer scale. Measurements of the threshold with various numerical apertures and different techniques are performed, revealing a noticeable threshold increase while decreasing the laser beam-focus size below ~10 μm. This unexpected result could be explained by the presence of micrometer-sized defects pre-existing in the SiO 2 sample.

This tutorial focuses on the new opportunities that may be harnessed when the operating wavelength of acceleration structures is reduced by more than 5 orders of magnitude from tens of centimeters to a fraction of a micro-meter. On the one hand, we show how a Bragg waveguide may be adapted to work as an acceleration structures and on the other hand, we examine particle acceleration by stimulated emission of radiation - a novel acceleration paradigm demonstrated recently. Implications on future medical accelerators are discussed.

A flexible method for fabricating shallow optical waveguides by using femtosecond laser writing of patterns on a metal coated glass substrate followed by ion-exchange is described. This overcomes the drawbacks of low index contrast and high induced stress in waveguides directly written using low-repetition rate ultrafast laser systems. When compared to conventional lithography, the technique is simpler and has advantages in terms of flexibility in the types of structures which can be fabricated.

The evanescent coupling of femtosecond laser written waveguides with elliptical and circular shape is investigated in detail. Elliptical waveguides are used to investigate directional tuning of the coupling properties in a square array by tilting the elliptical waveguides. This allows to specifically pronounce diagonal coupling. In contrast, directional insensitive coupling is demonstrated in a circular waveguide array based on circular waveguides.

Date of Conference: 1-4 October 2006 Conference name: Proceedings of SPIE, Active and Passive Optical Components for Communications VI One of the key challenges for the next-generation light sources such as X-FELs is to implement a timing stabilization and distribution system to enable ∼ 10 fs synchronization of the different RF and laser sources distributed in such facilities with distances up to a few kilometers. These requirements appear to be beyond the capability of traditional RF distribution systems based on temperature-stabilized coaxial cables. A promising alternative is to use an optical transmission system: A train of pulses generated from a laser with low timing jitter is distributed over length-stabilized fiber links to remote locations. The repetition frequency of the pulse train and its higher harmonics contain the synchronization information. At the remote locations, RF signals are extracted simply by using a photodiode and a suitable bandpass filter to pick the desired harmonic of the laser repetition rate. Passively mode-locked Er-doped fiber lasers provide excellent long-term stability. The laser must have extremely low timing jitter, particularly at high frequencies (>1 kHz). Ultimately, the timing jitter is limited by quantum fluctuations in the number of photons making up the pulse and the incoherent photons added in the cavity due to spontaneous emission. The amplitude and phase noise of a home-built laser, generating 100-fs, 1-nJ pulses, was characterized. The measured phase noise (timing jitter) is sub-10 fs. from 1 kHz to Nyquist frequency. In addition to synchronization of accelerators, the ultra-low timing jitter pulse source can find applications in next-generation telecommunication systems.

Rensselaer is establishing an educational training program, THz Science and Technology, with an interdisciplinary faculty team from Physics, Biology and Electrical, Computer & Systems Engineering. Students will be trained in three areas: THz electronics, THz data transfer and networking, and THz spectroscopy and imaging.

Although previous direct measurements of the microstructure-fiber continuum have all showed a smooth and stable spectrum, our cross-correlation frequency-resolved optical gating (XFROG) full-intensity-and-phase characterization of the continuum pulse, utilizing sum-frequency-generation with a pre-characterized reference pulse and the angle-dithered-crystal technique, indicates that fine-scale spectral structure exists on a single-shot basis, contrary to previous observations. In particular, deep and fine oscillations are found in the retrieved spectrum, and the retrieved trace contains a "measles" pattern, whereas the measured trace and the independently-measured spectrum are rather smooth. The discrepancy is shown to be the result of unstable single-shot spectral structure. Although the XFROG measurement is not able to directly measure the single-shot fine structure in the trace, the redundancy of information in FROG traces enables the retrieval algorithm to correctly recognize the existence of the spectral fine structure, and restore the structure in the retrieved trace and spectrum. Numerical simulations have supported our hypothesis, and we directly observed the fine spectral structure in single-shot measurements of the continuum spectrum and the structure was seen to be highly unstable, the continuum spectrum appearing smooth only when many shots are averaged. Despite the structure and instability in the continuum spectrum, coherence experiments also reveal that the spectral phase is rather stable, being able to produce well-defined spectral fringes across the entire continuum bandwidth.

Three commercial optical design programs are used to model familiar geometries in ultrafast optics. A set of macros has been created to calculate the pulse delay, group velocity dispersion (GVD), and third order dispersion (TOD) caused by components of an optical system. The programs have also been used to model a number of ultrafast pulse measurement systems using non-sequential ray tracing. This approach can provide evaluation, optimization, and insight into various pulse shaping schemes.

Applications of ultrafast optics to microwave technology are reviewed. A time domain broad band sparameter measurement technique has been demonstrated. On-wafer phase locking of a free running microwave source to the optical pulses is also reported. Some of its applications are discus''sed. I.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.