Silicon-based integrated interferometer with phase modulation driven by surface acoustic waves

Gorecki, Christophe; Chollet, Franck; Bonnotte, Éric; Kawakatsu, Hideki

doi:10.1364/ol.22.001784

Cited by 39 publications

(22 citation statements)

References 9 publications

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“…SAW thus can have very high energy confinement and attain large overlap with the optical modes of the planar waveguides to achieve efficient A/O modulation in compact devices. However, the highest operation frequency of such SAW-based integrated A/O devices that have been achieved was still below one GHz so far [11][12][13][14][15] .…”

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confidence: 99%

Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

Tadesse¹,

Li²

2014

Nat Commun

162

103

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Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally, these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acoustooptic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct, wideband link between optical and microwave photons for microwave photonics and quantum optomechanics.

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confidence: 99%

Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

Tadesse¹,

Li²

2014

Nat Commun

162

103

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“…2,3 As an alternative approach, Gorecki et al proposed the combination of surface acoustic waves ͑SAWs͒ with MachZehnder interferometers ͑MZIs͒ for WG modulators. 4,5 Here, the strain field of a SAW impinging perpendicularly to one of the interferometer arms introduces a periodic modulation of the transmitted light. More recently, de Lima et al 6 introduced an approach for acoustically driven MZI, where a single SAW simultaneously modulates the refractive index of both MZI arms with opposite phases, as illustrated in Fig.…”

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confidence: 99%

Acousto-optical multiple interference switches

Beck

Lima

Wiebicke

et al. 2007

Applied Physics Letters

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The authors introduce an alternative approach for acousto-optical light control based on the interference of light propagating through several waveguides, each subjected to a periodic refractive index modulation induced by a surface acoustic wave. The feasibility of the concept is demonstrated by the realization of an optical switch for arbitrary time intervals with an on/off contrast ratio of 20. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2768889͔The acousto-optical interaction provides a wellestablished process for controlling light beams in solids. 1 With the advent of integrated optics, approaches have been sought after to implement the required phase matching between the acoustic and optical waves propagating in waveguide ͑WG͒ structures. Examples are the acoustically induced coupling between neighboring WGs ͑Ref. 1͒ and the use of Umklapp scattering in photonic crystals. 2,3 As an alternative approach, Gorecki et al. proposed the combination of surface acoustic waves ͑SAWs͒ with MachZehnder interferometers ͑MZIs͒ for WG modulators. 4,5 Here, the strain field of a SAW impinging perpendicularly to one of the interferometer arms introduces a periodic modulation of the transmitted light. More recently, de Lima et al. 6 introduced an approach for acoustically driven MZI, where a single SAW simultaneously modulates the refractive index of both MZI arms with opposite phases, as illustrated in Fig. 1͑a͒. The opposite phase modulation of amplitude max per arm is achieved by simply spacing the WGs by an odd multiple of the half acoustic wavelength SAW .In this letter, we demonstrate an alternative concept for WG acousto-optical elements based on the modulation of several interferometer arms by a single SAW beam. These acousto-optic multiple interference devices ͑AOMIDs͒ provide integrated optics building blocks for functionalities such as switching, harmonic generation, and pulse shaping. 7 The feasibility of the AOMID concept is established by the realization of a WG on/off switch for arbitrary time periods.The AOMID concept is an extension of the acoustically driven MZIs of Fig. 1͑a͒ for a number N P ജ 2 of WG arms connected in parallel. 8 The configurations for N P =2 ͑corre-sponding to the simple MZI͒, N P = 4, and N P = 8 are illustrated in Figs. 1͑a͒-1͑c͒. In each case, the single mode WGs ͑numbered by the index p =1, ... ,N P ͒ are assumed to be identical and much narrower than SAW . The WGs are aligned perpendicularly to the SAW propagation direction and displaced laterally so as to experience SAW phases differing by a multiple of SAW =2 / N P . The amplitude max of the light phase shift upon propagation through the WGs is related to the WG length ᐉ and to the refractive index modulation ␦n induced by the SAW strain by max =2 ␦nᐉ / L , where L is the light wavelength. The use of symmetric Y-splitters in Fig. 1 ensures unity transmission in the absence of a SAW. Under the previous assumptions, the transmission T P of an AOMID with N P arms becomes:where f SAW is the SAW frequency. Figure 1͑d͒ comp...

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“…The modulator consists of a MZI driven by a surface acoustic wave ͑SAW͒ in the gigahertz range, where the length of the interaction region between the acoustic and optical waves ͑the active region͒ is reduced to approximately 15 m. The design used, which is a modified version of the acousto-optic MZI proposed by Gorecki et al,6 is based on the refractive index modulation of the interferometer arms by the wave fronts of a SAW propagating perpendicularly to the arms. The changes in refractive index are induced by the elasto-optic and electro-optic effects associated with the strain and piezoelectric fields, respectively.…”

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confidence: 99%

“…In our design, we introduce two fundamental modifications to increase the modulation efficiency and reduce the length of the active region. First, we enhance the modulation efficiency by modulating simultaneously both interferometer arms using the same SAW ͑in the original proposal, 6 only one of the arms is modulated͒. For that purpose, the MZI arms are separated by an odd multiple of SAW / 2, in order to experience refractive index changes of opposite phase during the passage of the SAW.…”

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Compact Mach-Zehnder acousto-optic modulator

Lima

Beck

Hey

et al. 2006

Applied Physics Letters

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The authors demonstrate a compact optical waveguide modulator based on a Mach-Zehnder interferometer driven by surface acoustic waves. The modulator was monolithically fabricated on GaAs with an active region length of approximately 15 m. It yields peak-to-peak modulation exceeding 90% of the average transmission and operation in the gigahertz frequency range. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2354411͔ Acousto-optic effects have been used for optical modulation for a long time, with the Bragg cells being probably the best known example. 1 The demand for fast and compact devices together with required phase matching, however, imposes several limitations on conventional acousto-optic devices in future generations of integrated photonics. Therefore, great attention has recently been devoted to alternative concepts for light modulation. A promising approach to increase the operation speed employs all-optical light control, which allows operation down to the subpicosecond time scales. 2 These devices are typically a few hundreds of microns long since they rely on optical nonlinearities that are usually small. An effective approach to reduce device dimensions employs photonic crystals ͑PhCs͒. Examples are thermo-optical switches based on a PhC Mach-Zehnder interferometer ͑MZI͒ with 12-m-long arms on AlGaAs/ GaAs system 3 as well as electro-optical switches based on carrier injection of 80-m-long silicon PhC-MZI. 4 In both cases the switching time is on the order of microseconds. Faster PhC-based all-optical switching devices have been realized in the ͑Al,Ga͒As system by taking advantage of the nonlinear properties of quantum dots embedded in the MZI arms. 5 PhC fabrication, however, requires a sophisticated technology with very strict tolerances.In this letter, we demonstrate a compact and monolithic modulator based on conventional ridge waveguides ͑WGs͒ on GaAs. The modulator consists of a MZI driven by a surface acoustic wave ͑SAW͒ in the gigahertz range, where the length of the interaction region between the acoustic and optical waves ͑the active region͒ is reduced to approximately 15 m. The design used, which is a modified version of the acousto-optic MZI proposed by Gorecki et al.,6 is based on the refractive index modulation of the interferometer arms by the wave fronts of a SAW propagating perpendicularly to the arms. The changes in refractive index are induced by the elasto-optic and electro-optic effects associated with the strain and piezoelectric fields, respectively. For photon energies away from electronic transitions-which is the case discussed here-the elasto-optical effect dominates. 7 The width of the WGs forming the arms is chosen to be much smaller than the acoustic wavelength ͑ SAW ͒ in order to ensure a constant modulation amplitude across the WG width. In our design, we introduce two fundamental modifications to increase the modulation efficiency and reduce the length of the active region. First, we enhance the modulation efficiency by modulating simultaneously both interferom...

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Silicon-based integrated interferometer with phase modulation driven by surface acoustic waves

Cited by 39 publications

References 9 publications

Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

Acousto-optical multiple interference switches

Compact Mach-Zehnder acousto-optic modulator

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