Broadband space-time wave packets propagating 70  m

Bhaduri, Basanta; Yessenov, Murat; Reyes, Danielle; Pena, Jessica; Meem, Monjurul; Fairchild, Shermineh Rostami; Menon, Rajesh; Richardson, Martin; Abouraddy, Ayman F.

doi:10.1364/ol.44.002073

Cited by 58 publications

(39 citation statements)

References 40 publications

(55 reference statements)

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“…These relations are a result of simple linear calculations based on the arrival time and waist position of the different frequencies, but more rigorous calculations using the Fourier-transform of the spatio-spectral field agree very well with the simple result [9]. We must note that the flying focus is physically different from the so-called diffraction-free space-time wave packets [17] shown recently to also travel at controllable velocities in free space and in transparent materials [18,19], and to maintain their non-diffractive nature for tens of meters [20,21]. In the flying focus scheme, the velocity different than c is only present within the extended focal region, and although the flying focus has an extended Rayleigh length, there is no diffraction-free nature of the beam outside of this region.…”

Section: Overview Of the Flying Focussupporting

confidence: 62%

Controlling the velocity of a femtosecond laser pulse using refractive lenses

Jolly¹,

Gobert²,

Jeandet³

et al. 2020

Opt. Express

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The combination of temporal chirp with a simple chromatic aberration known as longitudinal chromatism leads to extensive control over the velocity of laser intensity in the focal region of an ultrashort laser beam. We present the first implementation of this effect on a femtosecond laser. We demonstrate that by using a specially designed and characterized lens doublet to induce longitudinal chromatism, this velocity control can be implemented independent of the parameters of the focusing optic, thus allowing for great flexibility in experimental applications. Finally, we explain and demonstrate how this spatiotemporal phenomenon evolves when imaging the ultrashort pulse focus with a magnification different from unity.

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Section: Overview Of the Flying Focussupporting

confidence: 62%

Controlling the velocity of a femtosecond laser pulse using refractive lenses

Jolly¹,

Gobert²,

Jeandet³

et al. 2020

Opt. Express

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“…velocities tunable from 30c to −4c [58], group delays of ∼150 ps [59], propagation distances extending to 70 m [60,61], among other unique properties [62][63][64][65]. These attributes indicate the potential utility of ST wave packets in constructing an optical buffer.…”

mentioning

confidence: 97%

Demonstration of a Free-Space Optical Delay Line Using Space-Time Wave Packets

Yessenov

Abouraddy

2019

Frontiers in Optics + Laser Science APS/DLS

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An optical buffer having a large delay-bandwidth-product -a critical component for future all-optical communications networks -remains elusive. Central to its realization is a controllable inline optical delay line, previously accomplished via engineered dispersion in optical materials or photonic structures constrained by a low delay-bandwidth product. Here we show that space-time wave packets whose group velocity in free space is continuously tunable provide a versatile platform for constructing inline optical delay lines. By spatio-temporal spectral-phase-modulation, wave packets in the same or in different spectral windows that initially overlap in space and time subsequently separate by multiple pulse widths upon free propagation by virtue of their different group velocities. Delay-bandwidth products of ∼100 for pulses of width ∼1 ps are observed, with no fundamental limit on the system bandwidth. arXiv:1910.05616v1 [physics.optics] 12 Oct 2019The relentless increase in demand for communications bandwidth [1] has spurred developments in sub-systems that are critical for future optical networks, such as spatial-mode multiplexing [2-4] and ultrafast modulators [5]. A critical -but to date elusive -component is an optical buffer that alleviates data packet contention at optical switches by reordering the packets without an optical-to-electronic conversion [6]. Previous efforts addressing this challenge have exploited so-called 'slow light' [7,8], which refers to the reduction in the group velocity of a pulse traversing a selected material [9][10][11][12] or carefully designed photonic structure [13][14][15]. Despite the diversity of their physical embodiments [16], slow-light approaches typically rely on resonant optical effects and are thus limited by a delay-bandwidth product (DBP) on the order of unity.That is, the differential group delay with respect to a reference pulse traveling at c (the speed of light in vacuum) does not exceed the pulse width [17,18], which falls short of the requirements of an optical buffer [19]. Time-varying systems [20] can overcome this limit at the expense of increased implementation complexity. In one realization, a trapdoor mechanism in coupled resonators increases the storage time through externally controlled coupling [21] -but losses concomitantly increase in step with the delay. An alternate approach makes use of non-resonant recycling of orthogonal modes in a cavity [22]. A different strategy relies on transverse spatial structuring to reduce the group velocity in free space, but only a minute reduction below c has been detected to date [23,24]. Nevertheless, theoretical proposals suggest that pushing this approach to the limit may produce sufficiently large differential group delays for an optical buffer [25,26], but temporal spreading is associated with the propagation of these wave packets [27].Finally, a recent theoretical proposal suggests that optical non-reciprocity can help bypass the usual DBP limits [28], but doubts have been cast on this prospect [29,30].An alt...

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“…Introducing precise spatio-temporal spectral structure into a pulsed beam can profoundly modify its propagation characteristics [1,2]. For example, space-time (ST) wave packets [3] exhibit unique characteristics by virtue of their spatio-temporal spectral structure [4][5][6][7][8][9][10][11], including propagation-invariance [12][13][14][15][16], tunable group velocities [17,18], axial acceleration [19], ST Talbot selfimaging [20], and self-healing [21]. In contrast to earlier proposed localized waves [1,2], the group velocity of ST wave packets can depart significantly from that of conventional pulsed beams while remaining in the paraxial regime [22].…”

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confidence: 99%

Refraction of space-time wave packets in a dispersive medium

Yessenov,

Faryadras,

Benis

et al. 2021

Preprint

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Space-time (ST) wave packets are a class of pulsed optical beams whose spatio-temporal spectral structure results in propagation invariance, tunable group velocity, and fascinating refractive phenomena. Here, we investigate the refraction of ST wave packets at a planar interface between two dispersive, homogeneous, isotropic media. We formulate a new refractive invariant for ST wave packets in this configuration, from which we obtain a law of refraction that determines the change in their group velocity across the interface. We verify this new refraction law in ZnSe and CdSe, both of which manifest large chromatic dispersion at near-infrared frequencies in the vicinity of their band edges. ST wave packets can thus be a tool in nonlinear optics for bridging large group-velocity mismatches in highly dispersive scenarios.

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Broadband space-time wave packets propagating 70 m

Cited by 58 publications

References 40 publications

Controlling the velocity of a femtosecond laser pulse using refractive lenses

Controlling the velocity of a femtosecond laser pulse using refractive lenses

Demonstration of a Free-Space Optical Delay Line Using Space-Time Wave Packets

Refraction of space-time wave packets in a dispersive medium

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