Ultrafast optical switching of photonic crystals

Guina, Mircea; Suomalainen, Soile; Kalkman, Jeroen; Polman, A.; Jun, Yoonho; Hong, Wei; Norris, David J.; Vos, Willem L.

doi:10.1109/cleo.2006.4629083

Cited by 10 publications

(34 citation statements)

References 116 publications

(166 reference statements)

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“…The main mechanism in use for modifying the optical properties of solids is the excitation of free charge-carriers (FCs) [9][10][11][12][13][14][15]. FC excitation is frequently accomplished electrically, e.g., by an injection or a depletion of carriers with a bias voltage.…”

Section: Introductionmentioning

confidence: 99%

“…This plasma has a Drude-like contribution to the dielectric constant of the semiconductor, resulting in a refractive index that is lowered proportionally to the pump intensity (i.e., it is a nonlinear effect), reaching values as high as ∆n/n ∼ 10 −1 [13,15]. However, while the decrease of the refractive index occurs at time scales ranging from a few tens of femtoseconds (e.g., in silicon) to several picoseconds (e.g., in GaAs) [15], the refractive index relaxes to its equilibrium value at much longer time scales, depending on the dominant material relaxation mechanisms. These range from no less than several tens of picoseconds to a few nano-seconds [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond-scale switching based on excited free-carriers

et al. 2015

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Abstract:We describe novel optical switching schemes operating at femtosecond time scales by employing free carrier (FC) excitation. Such unprecedented switching times are made possible by spatially patterning the density of the excited FCs. In the first realization, we rely on diffusion, i.e., on the nonlocality of the FC nonlinear response of the semiconductor, to erase the initial FC pattern and, thereby, eliminate the reflectivity of the system. In the second realization, we erase the FC pattern by launching a second pump pulse at a controlled delay. We discuss the advantages and limitations of the proposed approaches and demonstrate their potential applicability for switching ultrashort pulses propagating in silicon waveguides. We show switching efficiencies of up to 50% for 100 fs pump pulses, which is an unusually high level of efficiency for such a short interaction time, a result of the use of the strong FC nonlinearity. Due to limitations of saturation and pattern effects, these schemes can be employed for switching applications that require femtosecond features but standard repetition rates. Such applications include switching of ultrashort pulses, femtosecond spectroscopy (gating), time-reversal of short pulses for aberration compensation, and many more. This approach is also the starting point for ultrafast amplitude modulations and a new route toward the spatio-temporal shaping of short optical pulses.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Femtosecond-scale switching based on excited free-carriers

et al. 2015

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“…While this result is expected for micron-scale periods (weak diffusion), it is quite un-intuitive for sub-micron periods. It originates from the relatively long thermalization times (e.g., with respect to silicon) [48]. This also means, for example, that heat diffusion will be less important in a semiconductor such as GaAs for which the thermalization is even slower [48].…”

Section: Discussionmentioning

confidence: 99%

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Sivan

Spector

2020

ACS Photonics

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Diffusion of heat in metals is a fundamental process which, surprisingly, received only a little attention from the research community. Here, we study heat diffusion on the femtosecond and few picoseconds time scales. Specifically, we identify the underlying time scales responsible for the generation and erasure of optically-induced transient Bragg gratings in metal films. We show that due to a interplay between the temporally and spatially nature of the thermo-optic response, heat diffusion affects the temperature dynamics in a partially indirect, and overall non-trivial way. Further, we show that heat diffusion affects also the nonlinear response in a way that was not appreciated before.1 In comparison, the source in the TTM has just the temporal profile of the absorbed power. 2 Note that the eTTM does not capture the increase of rate of energy transfer to the lattice during the thermalization time, as discussed in [18]; however, this effect should have, at most, a modest quantitative effect on the issues discussed in the current work.

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“…[3] we infer a large refractive index change of about ∆n'/n' = 2 %. The deduced refractive index change is predicted to strongly modify the density of states inside the crystal [15]. In experiments on the red part of the spectrum (ω probe < 6250 cm -1 ), the pump frequency was chosen to be (ω pump = 6450 cm -1 ).…”

Section: Ultrafast Switching Of Si Inverse Opalsmentioning

confidence: 99%

Ultrafast all-optical switching of 3D photonic band gap crystals

Hong

Kalkman

Jun

et al. 2007

Active Photonic Crystals

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We present ultrafast optical switching experiments on 3D photonic band gap crystals. Switching the Si inverse opal is achieved by optically exciting free carriers by a two-photon process. We probe reflectivity in the frequency range of second order Bragg diffraction where the photonic band gap is predicted. We observe a large frequency shift of up to 1.5% of all spectral features including the peak that corresponds to the photonic band gap. We also demonstrate large, ultrafast shifts of stop bands of planar GaAs/AlAs photonic structures. We briefly discuss how our results can be used in future switching and modulation applications.Keywords: photonic crystals, all-optical, switching, ultrafast, band gap, silicon, GaAs. ULTRAFAST SWITCHING EXPERIMENTSCurrently, many efforts are devoted to a novel class of three-dimensional meta-materials known as photonic crystals [1]. Spatially periodic variations of the refractive index commensurate with optical wavelengths cause the photon dispersion relations to organize in bands, analogous to electron bands in solids. Generally, frequency windows known as stop gaps appear in which modes are forbidden for specific wave vectors. Experimentally, stop gaps appear as peaks in reflectivity spectra. The strong dispersion in photonic crystals can be used to control the propagation direction of light. Fundamental interest in 3D photonic crystals is spurred by the possibility of a photonic band gap, a frequency range for which no modes exist at all [2].Exciting prospects arise when photonic band gap crystals are switched on ultrafast timescales. In particular, switching photonic band gap crystals provides dynamic control over the density of states that would allow the switching-on or -off of light sources in the band gap [3]. Furthermore, switching would allow the capture or release of photons from photonic band gap cavities [3]. Switching the directional properties of photonic crystals also leads to fast changes in the reflectivity, where interesting changes have been reported for Bragg stacks [4,5], 2D photonic crystals [6,7], and firstorder stop bands of 3D opaline crystals [8,9]. Ultrafast control of the propagation of light is essential to applications in active photonic integrated circuits [10].In this article we study ultrafast switching of inverse opal photonic band gap crystals. The crystals have a sufficiently large refractive index contrast for a band gap to open up in the range of second order Bragg diffraction, while in the range of first order Bragg diffraction a pseudo gap occurs. In the region of the band gap, switching is expected to lead to ultrafast changes in the density of states.

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Ultrafast optical switching of photonic crystals

Cited by 10 publications

References 116 publications

Femtosecond-scale switching based on excited free-carriers

Femtosecond-scale switching based on excited free-carriers

Ultrafast Dynamics of Optically Induced Heat Gratings in Metals

Ultrafast all-optical switching of 3D photonic band gap crystals

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