Programmable ultrashort-pulsed flying images

Abstract

We report the generation of programmable two-dimensional arrangements of ultrashort-pulsed fringe-less Bessel-like beams of extended depth of focus (referred to as needle beams) without truncating apertures. A sub-20-fs Ti:sapphire laser and a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) of high-fidelity temporal transfer in phase-only operation mode were used in the experiments. Axicon profiles with ultrasmall conical angles were approximated by adapted gray scale distributions. It was demonstrated that digitized image information encoded in amplitudephase maps of the needle beams is propagated over considerably large distances at minimal cross talk without the need for additional relay optics. This experiment represents a physical realization of Saari's proposal of spatio-temporally nondiffracting "flying images" on a few-femtosecond time scale.

Microscopy with self-reconstructing beams

“…No change in pulse shape and duration was found. This finding agrees with Bock et al [2009], who also state that the effect of LCoS devices becomes critical only below a pulse duration of τ = 6fs.…”

Spatially encoded localized wavepackets for ultrafast optical data transfer

“…Like Bessel beams, needle beams show extended focal zones, a high angular tolerance [6,7] and behave self-reconstructing [1]. Another unique property of ultrashort-pulsed needle beams consists in their capability to propagate with a quasi-nondiffracting characteristics in spatial as well as temporal domain over significantly extended range as it was clearly indicated in experiments with few-cycle pulses [8]. All the mentioned features make the concept of programmable needle beam arrays particularly attractive for ultrafast data transfer, processing and storage in planar-optical as well as free-space communication systems.…”

Modal liquid crystal microaxicon array

“…To solve this problem some manufacturers use a special anti-reflection coating to ensure that the influence of the pixellated structure is minimized and thus the diffraction losses. In addition, LCoS-SLMs have residual phase distortions and a limited resolution [22]. Another option has been reported [23], In this work a tunable MEMS axicon mirror array is proposed.…”

“…The use of microaxicons in arrays also has important applications such as ultrafast optical communications [14], generation of femtosecond Bessel beams [15], nondiffracting "flying images" [16], and high-resolution optical coherence tomography [17]. Despite this, few works in the literature have demonstrated the fabrication of microaxicon arrays.…”

“…As commented above, the fabrication processes proposed until now produce limitations in the microaxicon parameters. One solution is the use of liquid-crystal-on-silicon spatial light modulators (LCoSSLMs) [22]. Despite this, the main problem is the low phase shift achieved by this device (usually 2n) and the price.…”