High Extinction Ratio Hybrid Graphene-Silicon Photonic Crystal Switch

Abstract

In this letter, we demonstrate a compact optical switch realized by integrating a graphene layer with a silicon photonic crystal cavity fabricated using deep UV immersion lithography and a novel transfer printing approach. A 17-dB extinction ratio and 0.75-nm shift in the cavity resonance are measured for a swing voltage of only 1.2 V. The graphene layer is limited to 1 × 5 µm in size. The experimental results are linked to a theoretical model and used to predict possible improvements to the design.

Taking silicon photonics modulators to a higher performance level: state-of-the-art and a review of new technologies

“…Atomically thick 2D materials, the most prominent graphene, have received considerable interest in the last decade to implement efficient modulators by integration with Si/SiN PICs. 1,[153][154][155][156][157][158][159][160][201][202][203][204][205][206][207][208] The implementation of graphene-based modulators in SiPh involves the transfer of the graphene layer on a Si or SiN waveguide. 1 Mature and wafer-scale chemical vapor deposition is the widely adopted scheme to deposit graphene on a variety of metallic and dielectric substrates.…”

“…[283][284][285] The transfer of the graphene layer on a Si or SiN waveguide is performed after delaminating graphene from the substrate while adding a polymer carrier to handle the graphene film. 154,159 Recently, microtransfer printing technology has shown promising results to transfer graphene to the target substrate in an automatic fashion. 159 A single graphene layer, which is only a fraction of a nanometer thick, can absorb 2.3% of light 286 with a wavelength ranging from the visible to THz wavelengths (graphene is a gapless material).…”

“…154,159 Recently, microtransfer printing technology has shown promising results to transfer graphene to the target substrate in an automatic fashion. 159 A single graphene layer, which is only a fraction of a nanometer thick, can absorb 2.3% of light 286 with a wavelength ranging from the visible to THz wavelengths (graphene is a gapless material). Furthermore, graphene has a very high electron mobility of >100,000 cm 2 • V −1 • s −1 (silicon has a carrier mobility of 1400 cm 2 • V −1 • s −1 ).…”

“…Table 1 shows a rich landscape of SiPh modulators, where SiPh is incorporating a variety of other materials for implementing performant high-speed modulators. Modulation of amplitude by the Franz-Keldysh (FK) effect, 20,38,128,[133][134][135][136][137][138][139][140] quantum-confined Stark (QCS) effect, [141][142][143][144][145][146][147][148][149][150][151][152] and electrical gating, [153][154][155][156][157][158][159][160] or the modulation of phase by employing the plasma dispersion effect, [161][162][163][164][165][166] Pockels effect, [192][193][194][195][196][197][198][199][200] and inter-band transitions,…”

Tuning of Graphene-Based Optical Devices Operating in the Near-Infrared

“…This effect can be achieved by introducing doping using electrical and/or chemical gating, which shifts the Fermi energy from the Dirac point and, in turn, changes the optical response of graphene [6]. This approach opens the possibility of easily tuning graphene from a "lossy-dielectric" behaviour to the "quasi-metallic" region, which can be used to implement modulators (based on electro-optical graphene optical behaviour, Mach-Zehnder interferometers, rings, switches and Zeno-based modulators) [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], resonators [24][25][26], or can be applied to a wide variety of devices that operate at a specific resonance and require wavelength tuning [27][28][29]. It should be noted that the use of this property of graphene is not limited only to the NIR range; in this regard, electro-optical graphene terahertz modulators can be noted [30][31][32].…”