Progress on Waveguide-Integrated Graphene Optoelectronics

Graphene, a single layer of carbon atoms arranged in the form of hexagonal lattice, has many intriguing optical and electrical properties. However, due to the atomic layer thickness, light-matter interactions in the monolayer graphene are naturally weak when the light is normally incident to the material. To overcome this challenge, waveguide-integrated graphene optoelectronic devices have been proposed and demonstrated. In such coplanar configurations, the propagating light in the waveguide can significantly interact with the graphene layer integrated on the surface of the waveguide. The combination of photonic integrated circuits and graphene also enables the development of graphene devices by using silicon photonic technology, which greatly extends the scope of graphene’s application. Moreover, the waveguide-integrated graphene devices are fully CMOS-compatible, which makes it possible to achieve low-cost and high-density integration in the future. As a result, the area has been attracting more and more attention in recent years. In this paper, we introduce basic principles and research advances of waveguide-integrated graphene optoelectronics.

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Edge Couplers in Silicon Photonic Integrated Circuits: A Review

Applied Sciences ◽

10.3390/app10041538 ◽

2020 ◽

Vol 10 (4) ◽

pp. 1538 ◽

Cited By ~ 6

Author(s):

Xin Mu ◽

Sailong Wu ◽

Lirong Cheng ◽

H.Y. Fu

Keyword(s):

Integrated Circuits ◽

Optical Interconnects ◽

Low Cost ◽

Photonic Integrated Circuits ◽

High Refractive Index ◽

Grating Couplers ◽

Integration Density ◽

Silicon Photonic ◽

Optical Transmission Systems ◽

Structural Configurations

Silicon photonics has drawn increasing attention in the past few decades and is a promising key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon, and compatibility with current semiconductor fabrication process. Optical interconnects is an important issue in silicon photonic integrated circuits for transmitting light, and fiber-to-chip optical interconnects is vital in application scenarios such as data centers and optical transmission systems. There are mainly two categories of fiber-to-chip optical coupling: off-plane coupling and in-plane coupling. Grating couplers work under the former category, while edge couplers function as in-plane coupling. In this paper, we mainly focus on edge couplers in silicon photonic integrated circuits. We deliver an introduction to the research background, operation mechanisms, and design principles of silicon photonic edge couplers. The state-of-the-art of edge couplers is reviewed according to the different structural configurations of the device, while identifying the performance, fabrication feasibility, and applications. In addition, a brief comparison between edge couplers and grating couplers is conducted. Packaging issues are also discussed, and several prospective techniques for further improvements of edge couplers are proposed.

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