Optical Waveform Synthesis and Its Applications

Abstract

The quest for ever‐shorter optical pulses has been ongoing for over half a century. Although few‐cycle pulses have been generated for nearly 40 years, pulse lengths below the single‐cycle limit have remained an elusive goal for a long time. For this purpose, optical waveform synthesizers, generating high‐energy, high‐average‐power pulses via coherent combination of multiple pulses covering different spectral regions, have been recently developed. They allow unprecedented control over the generated optical waveforms, spanning an extremely broad spectral range from ultraviolet to infrared. Such control allows for steering strong‐field interactions with increased degrees of freedom. When driving high‐harmonic generation, tailored waveforms can produce bright attosecond pulse trains and even isolated attosecond pulses with tunable spectra up to the soft X‐ray range. In this paper recent progress on parametric and hollow‐core fiber waveform synthesizers is discussed. Newly developed seeding schemes; absolute, relative, and spectral phase measurement; and control techniques suitable for synthesizers are described. The progress on serial and parallel waveform synthesis based on Ti:sapphire and Ytterbium laser systems and their latest applications in high‐harmonic generation in gaseous and solid media, attosecond science, and laser wakefield acceleration is discussed.

Generation of polarization-controllable low-frequency THz radiations from single-layer graphene using incommensurate two-color laser pulses

“…Two-color laser can enhance the residual current in the y direction, the THz ellipticity is mostly determined by the THz intensities in the x and y directions, and the THz polarization direction is closely related to the phase difference between THz emissions in two directions. Note that our proposed scheme can be realized experimentally by combining several techniques available in the labs, such as the generation and measurement of THz emissions from single-layer graphene driven by single-color laser [35,38,47], the generation of highpower few-cycle mid-infrared laser pulses [48][49][50], and the synthesis of two-color laser pulses [51]. And it also increases the operation complication and the cost in the experiment.…”

Synthesis and Direct Sampling of Single-Cycle Light Transients by Electron Tunneling in a Nanodevice

“…Specifically, ultrashort pulses are spectrally broadened in a nonlinear medium, then the different spectral channels of the broadened laser pulses are compressed individually and combined together to generate a synthesized waveform. [4][5][6][7]12 Light-field-synthesis schemes for the generation of single-cycle pulses have been implemented for high-energy (>μJ) and low-repetition-rate (∼kHz) laser pulses, which are highly desirable to study nonlinear optical effects in atoms, molecules, and bulk materials. 13,14 Nevertheless, recent advancements in the fields of ultrafast near-field spectroscopy and imaging techniques demand new approaches to generate single-cycle laser pulses at much higher repetition rates [15][16][17][18][19].…”

“…Ultrashort light transients at the single-cycle limit can confine energy within an extremely short time interval, thereby enabling the observation and ultimate coherent control over ultrafast electronic currents in solids and quantum nanodevices. , The generation of single to sub-cycle laser pulses requires precise control over the amplitude and phase of the light components over one octave spectral bandwidth. − Over the past decade, several light-field synthesis techniques have been implemented to achieve this. Specifically, ultrashort pulses are spectrally broadened in a nonlinear medium, then the different spectral channels of the broadened laser pulses are compressed individually and combined together to generate a synthesized waveform. − , Light-field-synthesis schemes for the generation of single-cycle pulses have been implemented for high-energy (>μJ) and low-repetition-rate (∼kHz) laser pulses, which are highly desirable to study nonlinear optical effects in atoms, molecules, and bulk materials. , Nevertheless, recent advancements in the fields of ultrafast near-field spectroscopy and imaging techniques demand new approaches to generate single-cycle laser pulses at much higher repetition rates − (∼80 MHz).…”

“…Ultrashort light transients at the single-cycle limit can confine energy within an extremely short time interval, thereby enabling the observation and ultimate coherent control over ultrafast electronic currents in solids and quantum nanodevices. , The generation of single to sub-cycle laser pulses requires precise control over the amplitude and phase of the light components over one octave spectral bandwidth. − Over the past decade, several light-field synthesis techniques have been implemented to achieve this. Specifically, ultrashort pulses are spectrally broadened in a nonlinear medium, then the different spectral channels of the broadened laser pulses are compressed individually and combined together to generate a synthesized waveform. − , Light-field-synthesis schemes for the generation of single-cycle pulses have been implemented for high-energy (>μJ) and low-repetition-rate (∼kHz) laser pulses, which are highly desirable to study nonlinear optical effects in atoms, molecules, and bulk materials. , Nevertheless, recent advancements in the fields of ultrafast near-field spectroscopy and imaging techniques demand new approaches to generate single-cycle laser pulses at much higher repetition rates − (∼80 MHz). This has multiple advantages compared to low-repetition-rate laser pulses, e.g., constant heat load can be maintained at the apex of a nanotip in near-field measurements and extremely low signal levels can be measured with very high signal-to-noise levels. , The near-field enhancement at the apex of a nanotip in a scanning tunneling microscope ,, or scanning near-field optical microscope , also warrants the possibility of achieving very high local electric fields (>1 V/Å) with very low-energy laser pulses (at a high repetition rate) similar to the field strength in strong-field experiments performed with low-repetition-rate laser sources.…”