2D materials in electro-optic modulation: energy efficiency, electrostatics, mode overlap, material transfer and integration

Ma, Zhizhen; Hemnani, Rohit; Bartels, Ludwig; Agarwal, Ritesh; Sorger, Volker J.

doi:10.1007/s00339-017-1541-x

Cited by 13 publications

(7 citation statements)

References 17 publications

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“…This work focuses on charge-driven electro-absorption modulators (EAM) only, as opposed to electric field-driven designs, such as those based on Franz-Keldysh or Pockel's effect [15][16][17][18]. We mainly discuss three active materials only, namely silicon, indium-tin-oxide (ITO) and graphene, but briefly mention results regarding expected absorption of other two dimensional (2D) materials [19][20][21], quantum dots [22], and quantum wells [23,24]. The discussion thence includes a parametric study of achievable optical effective index changes as a function of the optical mode overlap factor with the active material, the materials own index change potential, and the effective mode's group index with bias.…”

Section: Electro-optic Modulator Challengesmentioning

confidence: 99%

Scaling vectors of attoJoule per bit modulators

Sorger

Amin

Khurgin

et al. 2017

J. Opt.

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Electro-optic modulation performs the conversion between the electrical and optical domain with applications in data communication for optical interconnects, but also for novel optical computing algorithms such as providing nonlinearity at the output stage of optical perceptrons in neuromorphic analog optical computing. While resembling an optical transistor, the weak lightmatter-interaction makes modulators 10 5 times larger compared to their electronic counterparts. Since the clock frequency for photonics on-chip has a power-overhead sweet-spot around tens of GHz, ultrafast modulation may only be required in long-distance communication, not for short on-chip links. Hence, the search is open for power-efficient on-chip modulators beyond the solutions offered by foundries to date. Here, we show scaling vectors towards atto-Joule per bit efficient modulators on-chip as well as some experimental demonstrations of novel plasmonic modulators with sub-fJ/bit efficiencies. Our parametric study of placing different actively modulated materials into plasmonic versus photonic optical modes shows that 2D materials overcompensate their miniscule modal overlap by their unity-high index change. Furthermore, we reveal that the metal used in plasmonic-based modulators not only serves as an electrical contact, but also enables low electrical series resistances leading to near-ideal capacitors. We then discuss the first experimental demonstration of a photon-plasmon-hybrid graphene-based electro-absorption modulator on silicon. The device shows a sub-1 V steep switching enabled by near-ideal electrostatics delivering a high 0.05 dB V −1 μm −1 performance requiring only 110 aJ/ bit. Improving on this demonstration, we discuss a plasmonic slot-based graphene modulator design, where the polarization of the plasmonic mode aligns with graphene's in-plane dimension; where a push-pull dual-gating scheme enables 2 dB V −1 μm −1 efficient modulation allowing the device to be just 770 nm short for 3 dB small signal modulation. Lastly, comparing the switching energy of transistors to modulators shows that modulators based on emerging materials and plasmonic-silicon hybrid integration perform on-par relative to their electronic counter parts. This in turn allows for a device-enabled two orders-of-magnitude improvement of electrical-optical co-integrated network-on-chips over electronic-only architectures. The latter opens technological opportunities in cognitive computing, dynamic data-driven applications systems, and optical analog computer engines including neuromorphic photonic computing.

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Section: Electro-optic Modulator Challengesmentioning

confidence: 99%

Scaling vectors of attoJoule per bit modulators

Sorger

Amin

Khurgin

et al. 2017

J. Opt.

Self Cite

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“…Even if the latter still enables high-speed modulation it requires a great deal of additional power, therefore we believe that integration strategies aiming to minimize cross-talk and thermal effect, using for instance thermal polymers [63] would give a pathway for a high speed modulation using ring resonators without trading off energy consumption. However, we note that there are several emerging materials such as ITO and Graphene that are explored for efficient modulation [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78], which include new modulation schemes and heterogeneous integration strategies, slow-light effects such as plasmon cavities. We now focus on the simulation of the architecture and its performance.…”

Section: Discussionmentioning

confidence: 99%

OE-CAM: A Hybrid Opto-Electronic Content Addressable Memory

et al. 2020

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A content addressable memory (CAM) is a type of memory that implements a parallel search engine at its core. A CAM takes as an input a value and outputs the address where this value is stored in case of a match. CAMs are used in a wide range of applications including networking, cashing, neuromorphic associative memories, multimedia, and data analytics. Here, we introduce a novel opto-electronic CAM (OE-CAM) utilizing the integrated silicon photonic platform. In our approach, we explore the performance of an experimental OE-CAM and verify the efficiency of the device at 25Gbit/s while maintaining the bit integrity under noise conditions. We show that OE-CAM enables a) two orders of magnitude faster search functionality resulting in b) a five orders of magnitude lower power-delay-product compared to CAMs implementations based on other emerging technologies. This remarkable performance potential is achieved by utilizing i) a high parallelism of wavelength-divisionmultiplexing in the optical domain, combined with ii) 10's of GHz-fast opto-electronic components, packaged in iii) integrated photonics for 10-100's ps-short communication delays. We further verify the upper optical input power limit of this OE-CAM to be given by parasitic nonlinearities inside the silicon waveguides, and the minimal detectable optical power at the back-end photoreceiver's responsivity given channel noise. Such energy-efficient and short-delay OE-CAMs could become a key component of functional photonic-augmented ASICS, co-processors, or smart sensors.

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“…Electro‐optic modulators take advantage of electro‐optic effects to electrically modulate the light properties. [ 71,72 ] They actively work as the electric‐to‐optic conversion in the optical coupling that is one of the major parts within the integrated photonic circuits. [ 73 ] Phare et al.…”

Section: Electro‐optic Effect and Its Applications For 2d Materialsmentioning

confidence: 99%

“…Electro-optic modulators take advantage of electro-optic effects to electrically modulate the light properties. [71,72] They actively work as the electric-to-optic conversion in the optical coupling that is one of the major parts within the integrated photonic circuits. [73] Phare et al demonstrated an electro-optic modulator with greatly increased modulation speed and efficiency enabled by modulating the resonator loss at the critical coupling.…”

Section: Modulatorsmentioning

confidence: 99%

Tunable Optical Properties of 2D Materials and Their Applications

Ren

et al. 2020

Advanced Optical Materials

154

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unlimited possibilities in the improvement of the performances of optoelectronic devices. [19-23] Beyond that, the properties of 2D materials can be tuned in situ by using different approaches [24-26] to expand the functionalities of optoelectronic devices. Out of them, the tunability in their optical properties has attracted great interest over the past decades where researchers dedicated to discovering various tuning methods to realize desired outcomes. [27,28] More excitingly, owing to the unprecedented electronic properties, high stretchability, magnetism, and thermal conductivity of 2D materials, different tuning approaches such as electrical gating, external strain stimuli, a static magnetic field, surface acoustic waves (SAWs), and thermal heating can be simultaneously adopted to participate the light-matter interaction, leading to the tailored and synergetic optical response of 2D materials. [29] Table 1 illustrates a brief advantages and weaknesses analysis between different optical tuning approaches of 2D and non-2D materials. There is a huge potential to revolutionize the optoelectronic devices by incorporating 2D materials with tunable optical properties. [30,31] So far, researchers have achieved flagship milestones in this area where a diverse set of high-performance optical devices are realized including modulators, photodetectors, optical sources, and optical switches. [32] In this review, we primarily focus on the theoretical and experimental researches of optical effects causing by various external stimuli in 2D materials. In Section 2, 2D materials with electro-optic effect and its application will be discussed, followed by piezophototronic effect and its application in Section 3. In Section 4, 2D materials with magneto-optic effect and its application will be discussed. Then, acousto-optic (AO) effect and its application, and thermo-optic (TO) effect and its application will be discussed in Sections 4 and 5, respectively. In the last section, the conclusion and perspective will be provided. 2. Electro-Optic Effect and Its Applications for 2D Materials 2.1. 2D Materials with Electro-Optic Effect In a broad sense, electro-optic effect is about an optical property change in the materials when applying an electric field. As shown in Figure 1, the refractive index of the material can be tuned in the presence of electric field due to the variation of charge carrier density. [29] This effect involves several Recent efforts have been heavily devoted to the development of next-generation optoelectronic devices based on 2D materials, due to their unique optical properties that are distinctly different from those of bulk counterparts. Given that the feature of flexible tunability is highly desired, various approaches have been demonstrated to efficiently modulate the optical properties, eventually enabling peculiar functionalities or realizing high-performance nanoscale devices. Here, this review focuses on recent advances in tuning the optical properties of 2D materials by external stimuli including elec...

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2D materials in electro-optic modulation: energy efficiency, electrostatics, mode overlap, material transfer and integration

Cited by 13 publications

References 17 publications

Scaling vectors of attoJoule per bit modulators

Scaling vectors of attoJoule per bit modulators

OE-CAM: A Hybrid Opto-Electronic Content Addressable Memory

Tunable Optical Properties of 2D Materials and Their Applications

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