Determination of nonlinear refractive index in a Ta2O5 rib waveguide using self-phase modulation

Tai, Chao Yi; Wilkinson, James S.; Perney, N.M.B.; Netti, M.C.; Cattaneo, Francesco; Finlayson, Chris E.; Baumberg, Jeremy J.

doi:10.1364/opex.12.005110

Cited by 81 publications

(39 citation statements)

References 13 publications

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“…Figure 1 shows the observed spectral broadening for 8 nJ pulse energy at 1610 nm. This is primarily attributed to self-phase modulation, in accordance with previous studies at 800 nm [1]. The dependence of …”

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“…Here we investigate Ta 2 O 5 rib planar waveguides as an alternative for compact optical devices with a small effective area that could enable the exploitation of nonlinear effects at low light intensity in the telecoms window. Ta 2 O 5 has been widely used as a high dielectric gate material for microelectronic devices, and multilayer dielectric mirrors, and more recently it was shown to possess a high nonlinear refractive index at 800 nm [1,14].Silicon dioxide ͑SiO 2 ͒ clad Ta 2 O 5 planar rib waveguides are grown following the methodology in [15]. We examine the nonlinear optical properties of 5-mm-long waveguides with 750 nm core thickness and 2.5 m (sample A) and 18 m (sample B) width.…”

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“…Silica optical fibers are currently used owing to their low loss. However, the small nonlinear refractive index of silica [1][2][3] requires high switching powers and very long interaction lengths. To achieve compact switching devices, a large nonlinear refractive index ͑n 2 ͒ is required.…”

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Chi 3 dispersion in planar tantalum pentoxide waveguides in the telecommunications window

2009

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We report on the dispersion of the third-order nonlinear susceptibility ( ͑3͒ or "Chi 3") in planar Ta 2 O 5 waveguides in the telecommunications spectral window. We utilize the observation of third-harmonic generation under ultrashort pulsed excitation as a reference-free characterization method of ͑3͒ and obtain a large nonlinear coefficient, 2 ϫ 10 −13 esu, at 1550 nm. Our observation of efficient third-harmonic generation in Ta 2 O 5 waveguides in the telecoms window reveals the potential of this material system in high-speed integrated nonlinear optical switches. © 2009 Optical Society of America OCIS codes: 160.4330, 230.7390, 190.2620 Fast low-power all-optical switches are a key component for high-bit-rate communication systems. Silica optical fibers are currently used owing to their low loss. However, the small nonlinear refractive index of silica [1-3] requires high switching powers and very long interaction lengths. To achieve compact switching devices, a large nonlinear refractive index ͑n 2 ͒ is required. Although many materials with a higher nonlinear refractive index than silica have been reported [2,4-6], there is a particular interest in those compatible with planar processing technologies, with minimal losses and absorption at a wide range of operating wavelengths, and good thermal and mechanical robustness. Silicon provides one potential candidate [7,8] but exhibits strong free carrier and twophoton absorption limiting device performance. Chalcogenide (e.g., As 2 S 3 ) glass is an alternative that does not exhibit two-photon absorption [9][10][11][12]; however, it has a relatively low damage threshold (9 GW/ cm 2 [13]) compared to Ta 2 O 5 [14]. Both of the above two examples have large normal material dispersion, which can be detrimental to wavelength division multiplexing applications but can be compensated by adjusting the waveguide geometry dimensions [7][8][9][10][11][12]. Here we investigate Ta 2 O 5 rib planar waveguides as an alternative for compact optical devices with a small effective area that could enable the exploitation of nonlinear effects at low light intensity in the telecoms window. Ta 2 O 5 has been widely used as a high dielectric gate material for microelectronic devices, and multilayer dielectric mirrors, and more recently it was shown to possess a high nonlinear refractive index at 800 nm [1,14].Silicon dioxide ͑SiO 2 ͒ clad Ta 2 O 5 planar rib waveguides are grown following the methodology in [15]. We examine the nonlinear optical properties of 5-mm-long waveguides with 750 nm core thickness and 2.5 m (sample A) and 18 m (sample B) width. Figure 1 shows a cross-sectional scanning electron microscope view of two waveguides. The samples are optically excited using an optical parametric amplifier tunable in the near IR (280 fs pulses) with no laser-induced damage to the waveguides.We characterize the nonlinear optical properties of the rib waveguides by spectrally and spatially resolving the guided optical modes at the end face of the rib structure in both the near-IR an...

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Chi 3 dispersion in planar tantalum pentoxide waveguides in the telecommunications window

2009

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“…The final waveguides consist of a thin gold layer with thickness t Au = 22, 27 and 35 nm, sandwiched between 26 nm-thick tantalum pentoxide adhesion layers, and silicon dioxide claddings ( Figure 1a). The linear and nonlinear optical properties of tantalum pentoxide are well-known, 29,30 and its use provides smaller propagation losses in plasmonic waveguides than metallic adhesion materials, such as titanium. 31 This symmetric arrangement provides a substantialpropagation length of LRSPPs of about 0.3-0.5 mm at a wavelength of 1030 nm depending on the gold layer thickness t Au .…”

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Nonlinear Dynamics of Ultrashort Long-Range Surface Plasmon Polariton Pulses in Gold Strip Waveguides

et al. 2016

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We study experimentally and theoretically nonlinear propagation of ultrashort long-range surface plasmon polaritons in gold strip waveguides. The nonlinear absorption of the plasmonic modes in the waveguides is measured with femtosecond pulses revealing a strong dependence of the third-order nonlinear susceptibility of the gold core on the pulse duration and layer thickness. A comprehensive model for the pulse duration dependence of the third-order nonlinear susceptibility is developed on the basis of the nonlinear Schrödinger equation for plasmonic mode propagation in the waveguides. The model accounts for the intrinsic delayed (noninstantaneous) nonlinearity of free electrons of gold as well as the thickness of the gold film, and is experimentally verified. The obtained results are important for the development of active plasmonic and nanophotonic components. 2Plasmonic nanostructures represent a unique platform for many linear and nonlinear optical applications. 1 A great variety of plasmonic waveguides for integrated optics, 2,3 nanofocusing, 4,5 sensing, 6,7 lasing and amplification of light 8,9 has been proposed. In particular, special attention has recently been paid to the nonlinear optical properties of plasmonic waveguides, hybrid plasmonic waveguides, and other elements important for future nanophotonic communication approaches. [10][11][12] Bulk metals, thin metal layers, and plasmonic metamaterials have been investigated in the nonlinear regime. [13][14][15] The nonlinear propagation of surface plasmon polaritons (SPPs) in plasmonic waveguides can be studied in terms of either the second-order nonlinearity, 16,17 or the third-order nonlinearity. 18,19 The latter is particularly important because it is present in all materials. In metals, it mainly arises due to hot-electron contributions from changes of the intrinsic electronic temperature after absorption of the incident light. Typically, the electron relaxation time in noble metals is on the few-picosecond scale, 18,19 implying that their nonlinear susceptibility can depend on the laser pulse duration if it is shorter than or comparable with the electron relaxation time. 20 The majority of the experimental data on the third-order nonlinear susceptibility of gold were collected near the interband transitions in a wavelength range of 532-630 nm for pulse durations between 100 fs and 1 ns. 20 Most results were obtained with the z-scan method, reporting very high values of the third-order susceptibility in the range of 10 -16 -10 -15 m 2 /V 2 . [21][22][23][24] However, the linear propagation losses of SPPs in Au-based waveguides, which are also related to the same interband transitions, are very high (~30-40 dB/mm) in this wavelength range. 25 On the other hand, nanophotonic and plasmonic devices are extensively exploited in the infrared (IR) wavelength range. 2,3 The propagation losses of long-range SPPs (LRSPPs) in Au-based waveguides can be ~2-5 dB/mm at the telecommunication wavelengths. 25 Meanwhile, the third-3 order susceptibility of...

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“…Tantala (Ta 2 O 5 ) has already been used as a host for rare earth ions [9][10][11], with lasing being achieved only in Nd:Ta 2 O 5 to date [9]. This, combined with high refractive index (>2.0), moderate phonon energy for high radiative efficiency [12], a large third order non-linearity [13], and high photosensitivity [14], makes it an ideal material for realising multifunctional PLCs.…”

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Waveguiding and photoluminescence in Er3+-doped Ta2O5 planar waveguides

Subramanian

Otón

Wilkinson

et al. 2009

Journal of Luminescence

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The optimization of erbium-doped Ta 2 O 5 thin film waveguides deposited by magnetron sputtering onto thermally oxidized silicon wafer is described. Optical constants of the film were determined by ellipsometry. For the slab waveguides, background losses below 0.4 dB/cm at 633 nm have been obtained before post-annealing. The samples, when pumped at 980 nm yielded a broad photoluminescence spectrum (FWHM~50 nm) centered at 1534 nm, corresponding to 4 I 13/2 -4 I 15/2 transition of Er 3+ ion. The samples were annealed up to 600 ƕ C and, both photoluminescence power and fluorescence lifetime increase with post-annealing temperature and a fluorescence lifetime of 2.4 ms was achieved, yielding promising results for compact waveguide amplifiers.

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Determination of nonlinear refractive index in a Ta2O5 rib waveguide using self-phase modulation

Cited by 81 publications

References 13 publications

Chi 3 dispersion in planar tantalum pentoxide waveguides in the telecommunications window

Chi 3 dispersion in planar tantalum pentoxide waveguides in the telecommunications window

Nonlinear Dynamics of Ultrashort Long-Range Surface Plasmon Polariton Pulses in Gold Strip Waveguides

Waveguiding and photoluminescence in Er3+-doped Ta2O5 planar waveguides

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