Tunable Nanophotonic circuits based on phase change materials

Paper presented at European\Phase Change and Ovonics Symposium, 2013-09-08, 2013-09-10, BerlinWe present preliminary results of the characterization of the optical response of GeSbTe (GST) thin-films integrated with SiN nanophotonic circuits at telecom wavelengths. Transmission measurements are carried out GST thin-films of varying width deposited on top of ring resonators. The nanophotonics circuits are fabricated and optimized in order to find the best response when GST is placed atop the waveguiding layer. Our results for the absorption/transmission properties at different phase states of GST thin-films paves the way towards a all-photonic non-volatile memories

Mixed-Mode Electro Optical Properties of Ge2Sb2Te5

This is the author accepted manuscript.In this paper we present ongoing work on a novel alternative mode of operation of phase change materials, specifically Ge2Sb2Te5: mixed-mode electro-optical operation, which offers a new set of potential applications for this material

New 'Mixed-Mode' Optoelectronic Applications Possibilities using Phase-Change Materials and Devices

To date the main applications of phase-change materials and devices have been limited to the provision of non-volatile memories. Recently, however, the potential has been demonstrated for using a phase-change approach for the provision of entirely new concepts in optoelectronics, including phase-change displays, integrated phase-change photonic memories, optical modulation and optical computing [1-3]. Such novel applications are enabled by the ability of phase-change devices to operate in a 'mixed-mode' configuration, where the excitation is provided electrically and the sensing is carried out optically, or vice-versa. Exploitation of this mixed-mode is made possible in phase-change materials due to the large and simultaneous changes that occur in both refractive index and electrical resistivity on transformation between amorphous and crystalline states. In this paper, based on studies part-funded by the NSF Materials World Network, we present recent results of the use of such mixed-mode operation to provide new applications, including a demonstration of phase-change optoelectronics devices that can be used to make ultrathin all-solid-state colour displays of ultrahigh resolution [1], and hybrid integrated phase-change photonic circuits that offer both a low-power, multi-level memory capability and a computing functionality [2,3]. As so often mentioned by the late (and sadly missed) Stanford Ovhinsky at previous MRS meetings [4], phase-change materials have the potential to provide us with so much more than simple digital memory - a potential that we are now beginning to realize and exploit. [1] P Hosseini, C D Wright and H Bhaskaran, Nature 511, 206 (2014) [2] C Rios , P Hosseini , C D Wright , H Bhaskaran and W H P Pernice, Advanced Materials 26, 1372 (2014) [3] C D Wright, Y Liu, K I Kohary, M M Aziz, R J Hicken, Advanced Materials 23, 3408 (2011) [4] S R Ovshinsky and B Pashmakov, MRS Proceedings 803, 49 (2004

Novel applications possibilities for phase-change materials and devices

Paper presented at European\Phase Change and Ovonics Symposium 2013, 2013-09-08, 2013-09-10, BerlinPhase-change materials and devices are most widely known for their use in optical and electrical non-volatile memory applications. Recently however the potential has been demonstrated for using phase-change materials and devices for a range of novel applications, including the provision of electronic 'mimics' of biological synapses and neurons (and their associated use in neuromorphic computing) and the provision of arithmetic and logic functionality. Furthermore, such neuromorphic, arithmetic and logic capabilities of phase-change materials and devices are accessible in both the optical (photonic) and the electrical (electronic) domains, or indeed via a 'mixed-mode' approach in which excitation is in the optical domain and detection is electrical, or vice-versa. This versatility of operation opens up the route towards various intriguing possibilities, such as 'all-optical' memory and computing devices, or the development of an optical analogue of the memristor, the so-called 'memflector'. In this paper we discuss such novel applications possibilities for phase-change materials and devices and present proof-of-principle of some of the underlying concepts

High Q micro-ring resonators fabricated from polycrystalline aluminum nitride films for near infrared and visible photonics

We demonstrate wideband integrated photonic circuits in sputter-deposited aluminum nitride (AlN) thin films. At both near-infrared and visible wavelengths, we achieve low propagation loss in integrated waveguides and realize high-quality optical resonators. In the telecoms C-band (1520-1580 nm), we obtain the highest optical Q factor of 440,000. Critical coupled devices show extinction ratio above 30 dB. For visible wavelengths (around 770 nm), intrinsic quality factors in excess of 30,000 is demonstrated. Our work illustrates the potential of AlN as a low loss material for wideband optical applications

Interlaboratory study on Sb2S3 interplay between structure, dielectric function, and morphous-to-crystalline phase change for photonics

Antimony sulfide, Sb2S3, is interesting as the phase-change material for applications requiring high transmission from the visible to telecom wavelengths, with its band gap tunable from 2.2 to 1.6 eV, depending on the amorphous and crystalline phase. Here we present results from an interlaboratory study on the interplay between the structural change and resulting optical contrast during the amorphous-to-crystalline transformation triggered both thermally and optically. By statistical analysis of Raman and ellipsometric spectroscopic data, we have identified two regimes of crystallization, namely 250_C % T < 300_C, resulting in Type-I spherulitic crystallization yielding an optical contrast Dn _ 0.4, and 300 % T < 350 _ C, yielding Type-II crystallization bended spherulitic structure with different dielectric function and optical contrast Dn _ 0.2 below 1.5 eV. Based on our findings, applications of on-chip reconfigurable nanophotonic phase modulators and of a reconfigurable high-refractive-index core/phase-change shell nanoantenna are designed and proposed.The authors acknowledge the support from the European Union’s Horizon 2020 research and innovation program (No 899598 - PHEMTRONICS)

Polycrystalline diamond photonic waveguides realized by femtosecond laser lithography

In recent years, the perception of diamond has changed from it being a pure gemstone to a universal high-tech material. In the field of photonics, an increased interest is emerging due to its outstanding optical properties, such as its high refractive index, a spectrally wide transmission window, and high Raman coefficient. Furthermore, the capability to host color defects for room temperature single photon generation makes diamond an attractive platform for quantum photonics. Known as nature's hardest material, the fabrication and handling of crystalline diamond for integrated optics remains challenging. Here, we report on the fabrication of three-dimensional Type III depressed cladding waveguides in polycrystalline diamond substrates by direct laser writing. Single mode waveguiding is demonstrated in the near-infrared telecommunication C-band. We believe that this enables the fabrication of three-dimensional large-scale photonic circuits, which are essential for advanced classical and quantum diamond photonics

Purcell-enhanced emission from individual SiV − center in nanodiamonds coupled to a Si 3 N 4 -based, photonic crystal cavity

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Purcell-enhanced emission from individual SiV− center in nanodiamonds coupled to a Si3N4-based, photonic crystal cavity

Hybrid quantum photonics combines classical photonics with quantum emitters in a postprocessing step. It facilitates to link ideal quantum light sources to optimized photonic platforms. Optical cavities enable to harness the Purcell-effect boosting the device efficiency. Here, we postprocess a free-standing, crossed-waveguide photonic crystal cavity based on Si3N4 with SiV− center in nanodiamonds. We develop a routine that optimizes the overlap with the cavity electric field utilizing atomic force microscope (AFM) nanomanipulation to attain control of spatial and dipole alignment. Temperature tuning further gives access to the spectral emitter-cavity overlap. After a few optimization cycles, we resolve the fine-structure of individual SiV− centers and achieve a Purcell enhancement of more than 4 on individual optical transitions, meaning that four out of five spontaneously emitted photons are channeled into the photonic device. Our work opens up new avenues to construct efficient quantum photonic devices