Femtosecond spatial pulse shaping at the focal plane (original) (raw)

Femtosecond pulse shaping using spatial light modulators

Review of Scientific Instruments, 2000

We review the field of femtosecond pulse shaping, in which Fourier synthesis methods are used to generate nearly arbitrarily shaped ultrafast optical wave forms according to user specification. An emphasis is placed on programmable pulse shaping methods based on the use of spatial light modulators. After outlining the fundamental principles of pulse shaping, we then present a detailed discussion of pulse shaping using several different types of spatial light modulators. Finally, new research directions in pulse shaping, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed.

Pulse-Shaping Techniques Theory and Experimental Implementations for Femtosecond Pulses

Advances in Solid State Lasers Development and Applications, 2010

Femtosecond pulses are used in many fields due to their specificities of extreme short duration, ultra high peak power or large spectral bandwidth. Since the early days of the laser in the 60s, there has been a continous quest to generate shorter and or higher peak power pulses. Reliable generation of pulses below 100fs occurred the first time in 1981 with the invention of the colliding pulse modelocked (CPM) ring dye laser . Despite relative low energy per pulses, the ultrashort pulse duration leads to peak power large enough for non linear pulse compression culminating in pulses as short as 6fs in the visible. Recent advances in laser technology as the use of solid-state gain media, laser diode pumping, fiber laser, have led to simple, reliable, turn key ultrashort laser oscillators with pulse duration ranging form few ps down to 5fs. Limitation to pulse energy in the range of a microJoule or less in the CPM laser has been overcomed by the Chirped Pulse Amplification (CPA) technique (Strickland D., Mourou G., (1985)). This technique is the optical transposition of a Radar technique developped during the second world war. The basic principle is to spread in time i.e to stretch the ultrashort pulse before amplification. Indeed limitation of the pulse amplification because of the damage threshold of the optics is mainly due to the pulse peak power. A stretch ratio of a million gives the ability to amplify the stretched pulse, without optical damage, by a factor of a million from less than a microJoule to more than a Joule per pulse. After amplification, recompression of the pulse is achieved by an optical set-up that has a very high damage threshold. To obtain the highest peak power, the pulse duration has to be "Fourier transform limited", ie its spectral phase is purely linear. The compensation of the chirp and higher spectral phase order is highly simplified by the ability to introduced an arbitrarly shaped spectral phase. Application of these ultrashort pulses requires to control of optimize their temporal shape. Dispersion of materials and optical devices has been used to compress, stretch or replicate the pulses. Limitations on the ability to control the pulse temporal shape by classical optical devices have lead to the development of arbitrary pulse shapers. These devices are linear Source: Advances in Solid-State Lasers: Development and Applications, Book edited by: Mikhail Grishin, ISBN 978-953-7619-80-0, pp. 630, February 2010, INTECH, Croatia, downloaded from SCIYO.COM

Femtosecond Laser Pulses: Generation, Measurement and Propagation

2021

In this contribution some basic properties of femtosecond laser pulse are summarized. In sections 2.1-2.5 the generation of femtosecond laser pulses via mode locking is described in simple physical terms. In section 2.6 we deal with measurement of ultrashort laser pulses. The characterization of ultrashort pulses with respect to amplitude and phase is therefore based on optical correlation techniques that make of the short pulse itself. In section 3 we start with the linear properties of ultrashort light pulses. However, due to the large bandwidth, the linear dispersion is responsible for dramatic effects. To describe and manage such dispersion effects a mathematical description of an ultrashort laser pulse is given first before we continue with methods how to change the temporal shape via the frequency domain. The chapter ends with a paragraph of the wavelet representation of an ultrashort laser pulse.

Automated spatial and temporal shaping of femtosecond pulses

Optics Communications, 1998

The use of a liquid crystal spatial light modulator for the simultaneous spatial and temporal shaping of ultrafast optical pulses is demonstrated. A commercially available liquid crystal mask filters spatially dispersed frequency components in the Ž . horizontal direction, and spatial or wavevector components in the vertical direction. As an illustration, a coherent pulse sequence with nine spatial features and two temporal features per spatial feature is produced. q

Pulse shaping of octave spanning femtosecond laser pulses

2007

Characterization and pulse shaping of octave spanning femtosecond lasers poses a significant challenge. We have constructed a grating-based pulse shaper for an ultra-broad-bandwidth (620-1020 nm) femtosecond laser, and used it to compensate the phase distortions of the laser, spatial-light modulator and optics within 0.1 rad accuracy accross the entire bandwidth using Multiphoton Intrapulse Interference Phase Scan (MIIPS) without a precompressor. The compensated transform limited pulses generated a second harmonic spectrum with a 12,260 cm -1 spectral width. Binary phase modulation was introduced by this pulse shaping system to demonstrate high resolution control of the second harmonic generation spectrum.

Spatial shaping of femtosecond beam for controlling attosecond pulse

2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019

When an intense femtosecond (fs) pulse non-linearly interacts with ionizing matter, it leads to the generation of bursts of extreme ultra violet (XUV) coherent irradiations having ultrashort pulse duration in attoseconds. Here, we present systematic experiments to show how the high-order harmonics generation is modulated with a spatially shaped fs-laser beam. The spatial shaping of fs-pulses has been induced with the alteration in hard aperture from 8-25 mm diameter. The experimental parameters such as incident power and gas pressure has been optimized to efficiently generate the harmonics in our system. While changing the aperture size of intense fs-beam, we observed unique space-time coupling effects in the shapes of individual harmonics beam.

Prospects of ultrafast pulse shaping

Curr. Sci, 2002

Availability of femtosecond solid-state lasers around the world has spurred a lot of technological activity in the femtosecond timescale and has also given us a tool to probe and gain more insight into the fundamentals of physics, chemistry and biology. An eventual prospect of controlling and manipulating some of the hitherto impossible tasks, can perhaps now be dreamt of. In this review we give a brief account of some of the promising techniques for ultrafast laser pulse shaping and then list some of the exciting prospects.

Ultrashort laser pulse beam shaping

Applied optics, 2003

We calculated the temporal and spatial characteristics of an ultrashort laser pulse propagating through a diffractive beam-shaping system that converts a Gaussian beam into a beam with a uniform irradiance profile that was originally designed for continuous waves ͓Proc. SPIE 2863, 237 ͑1996͔͒. The pulse front is found to be considerably curved for a 10-fs pulse, resulting in a temporal broadening of the pulse that increases with increasing radius. The spatial intensity distribution deviates significantly from a top-hat profile, whereas the fluence shows a homogeneous radial distribution.