Graphene microheater for phase change chalcogenides based integrated photonic components [Invited]

Abstract

In order to effectively control the state of an active integrated photonic component based on chalcogenide phase change materials, an efficient microheater operating at low voltage is required. Here, we report on the design of a graphene based microheater. The proposed system contains two separate graphene layers between which the phase change material cell of Ge2Sb2Te5 is placed. Three distinct switching possibilities are explored, using only the bottom layer, only the top layer or both graphene layers. A detailed investigation of the heater parameters is performed to optimise switching performance. A self-consistent multiphysics simulation of the crystallization process in the phase change material cell is conducted demonstrating the switching capabilities of the proposed design.

On-Chip Reconfigurable and Ultracompact Silicon Waveguide Mode Converters Based on Nonvolatile Optical Phase Change Materials

“…The phase transition temperature of Sb 2 Se 3 is 473 K and the melting temperature of Sb 2 Se 3 is 893 K [ 33 , 34 ], where the upper temperature limit of the proposed device is 1100 K. From Figure 10 , the required temperatures for the phase change of Sb 2 Se 3 material can be achieved using the proposed graphene microheater. The graphene microheater is more efficient than other metal heaters because of the high thermal conductivity and low heat capacity of graphene [ 43 , 44 ]. In addition, the phase transition and melting temperatures of Sb 2 Se 3 are clearly lower than the melting temperatures of silicon, silica, graphene, and Al 2 O 3 , thus the phase transition process will not damage the proposed device.…”

“…The thicknesses of the Al 2 O 3 and graphene layers are H 1 (=20 nm) and H 3 (=0.35 nm), respectively. The graphene layer works as an efficient microheater because of its high thermal conductivity and low heat capacity [ 43 , 44 ]. The optical absorption loss of graphene could be quite low as the chemical potential of graphene is larger than 0.4 eV owing to the Pauli blocking mechanism [ 45 , 46 ].…”

A Review of Capabilities and Scope for Hybrid Integration Offered by Silicon-Nitride-Based Photonic Integrated Circuits

“…To overcome this drawback, Fang et al proposed the implementation of a layer of indium tin oxide (ITO) as an external transparent heater to switch the PCM phase between different states on SOI-based ring resonators [203], achieving an extinction ratio of over 30 dB near 1550 nm, proving the compatibility of ITO as a heater for future PCM-based SiN building blocks. Lately, graphene heaters are emerging as a possible solution to control the PCM temperature in photonic integrated circuits [213][214][215], see Figure 8i. Even though a relatively large amount of progress has been achieved in ITO and doped silicon-based heaters, graphene can reduce the switching energy and increase the speed maintaining a relatively low loss and the compatibility with the SiN platform [214].…”

“…(h) Microscope image of a SiN MZI with a Sb 2 S 3 cell deposited in one of the arms; reproduced from [207] under a CC BY 4.0 license. (i) Schematic of an integrated photonic graphene microheater for phase change chalcogenides on SiN building blocks; reproduced from [215] under a CC BY 4.0 license. This method can be applied to correct fabrication variations and for the reconfiguration of photonic circuits based on RRs, or other coupling devices such as splitters based on Mach-Zender interferometers.…”

“…(h) Microscope image of a SiN MZI with a Sb 2 S 3 cell deposited in one of the arms; reproduced from[207] under a CC BY 4.0 license. (i) Schematic of an integrated photonic graphene microheater for phase change chalcogenides on SiN building blocks; reproduced from[215] under a CC BY 4.0 license.…”