Chirped Pulse Trains for Quasi-Phase-Matching High Harmonic Generation

Adaptive shaping of laser beams for high-harmonic generation applications

“…Coherent sources of extreme-ultraviolet (XUV) radiation with pulses on the attosecond time scale are ideal for probing the dynamics of the molecular and subatomic scales [15,24,25]. Synchrotrons and free electron lasers (FELs) are excellent sources of incredibly bright XUV radiation, however the kilometre-scale size and build costs (in the millions or even billions of pounds) strictly limit access to these sites [3,26]. At XUV wavelengths the difficulty to obtain lasing stems from the required pump power which scales with λ −4 [27].…”

“…One application of HHG is for diffractive imaging [26,33]. The smallest structure of size d that can be imaged is given by d = Kλ/A, where K is a numerical constant that depends on the spatial coherence of the illumination of the object plane and A is the aperture of the optical system.…”

“…The imaging of biological samples with HHG is of particular interest due to the K-shell absorption edges of oxygen and carbon at 2.3 nm and 4.4 nm respectively. Within this window water is transparent, which leads to contrast differences throughout different tissue types [26,33].…”

“…Due to dispersion within this medium, the phase velocities for the fundamental and harmonic frequencies vary throughout the medium [26]. This leads to interference between the harmonic field contributions generated at different positions in the generating medium.…”

“…The TSM as illustrated in figure 2.11 follows these distinct steps [26,48,67]: releasing an XUV photon (dashed black).…”