CMOS-compatible all-optical modulator based on the saturable absorption of graphene

Huang

Advanced Optical Materials

et al. 2021

Palladium diselenide (PdSe2) exhibits considerable potential for application in broadband optoelectronic devices. In this work, the broadband nonlinear optical performance and ultrafast carrier dynamics from ultraviolet to near‐infrared of a trilayer PdSe2 are systematically studied. PdSe2 is found to achieve a giant saturable absorption performance. The modulation depth is 22.47% at 520 nm, whereas the nonsaturable loss and saturation intensity are only 3.83% and 15.47 GW cm−2, respectively, which are better than those of many 2D semiconductors. Based on these findings, a PdSe2‐based visible light thresholder is proposed, its function is to extract an undetectable pulse signal drowned in strong stochastic noise and thereby improve the signal‐to‐noise ratio. Pump–probe technique, along with first‐principles calculation and transient absorption spectra, reveals the intrinsic recombination mechanism, including Auger scattering and trap saturation. This work is expected to establish the foundation for the development of next‐generation PdSe2‐based devices in optoelectronics and visible light communication.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Broadband Nonlinear Photoresponse and Ultrafast Carrier Dynamics of 2D PdSe₂

Huang

Advanced Optical Materials

et al. 2021

“…Graphene also frequently showed in all-optical integrated modulators by several special methods, such as free space illumination, [141,142] microring resonator assisted by thermooptical effect [30,131,143] and saturable absorption on optical waveguides. [37,144] Inspired by the all-optical modulator on the silicon photonic crystal cavity, where the graphene is covered on the whole substrate illuminated by 1064 nm laser beam from free space, [145] several waveguide-based works were demonstrated. Sun et al employed dielectric-loaded waveguide [141] and plasmonic waveguide [142] to implement the graphene all-optical modulator in each waveguide structure.…”

Section: Graphene-based Modulatorsmentioning

confidence: 99%

“…[ 37 ] The same method was investigated on a straight waveguide with a response time of 1.65 ps. [ 144 ] With the development of graphene all‐optical modulators, saturable absorption is undoubtedly the most suitable method for all‐optical modulation. The fast response time caters for high speed optical communications, but the extinction ratio needs to be improved by further enhanced optical structures.…”

Section: D Material‐based Modulatorsmentioning

confidence: 99%

2D Materials Enabled Next‐Generation Integrated Optoelectronics: from Fabrication to Applications

et al. 2021

2D materials, such as graphene, black phosphorous and transition metal dichalcogenides, have gained persistent attention in the past few years thanks to their unique properties for optoelectronics. More importantly, introducing 2D materials into silicon photonic devices will greatly promote the performance of optoelectronic devices, including improvement of response speed, reduction of energy consumption, and simplification of fabrication process. Moreover, 2D materials meet the requirements of complementary metal‐oxide‐semiconductor compatible silicon photonic manufacturing. A comprehensive overview and evaluation of state‐of‐the‐art 2D photonic integrated devices for telecommunication applications is provided, including light sources, optical modulators, and photodetectors. Optimized by unique structures such as photonic crystal waveguide, slot waveguide, and microring resonator, these 2D material‐based photonic devices can be further improved in light‐matter interactions, providing a powerful design for silicon photonic integrated circuits.

“…By picking up an additional layer of graphene, a Gr/hBN/Gr heterostructure is formed. In [61], a waveguide-integrated all-optical graphene modulator with partially suspended graphene was demonstrated. There, a PMMA/Gr film was transferred onto the waveguides and patterned by EBL to control the modulation depth of the device.…”

Section: Modulation Performancementioning

confidence: 99%

High-Performance All-Optical Modulator Based on Graphene-hBN Heterostructures

Alaloul,

Khurgin

2022

Preprint

Graphene has emerged as an ultrafast photonic material for on-chip all-optical modulation. However, its atomic thickness limits its interaction with guided optical modes, which results in a high switching energy per bit or low modulation efficiencies. Nonetheless, it is possible to enhance the interaction of guided light with graphene by nanophotonic means. Herein, we present a practical design of an all-optical modulator that is based on graphene and hexagonal boron nitride (hBN) heterostructures that are hybrid integrated into silicon slot waveguides. Using this device, a high extinction ratio (ER) of 7.3 dB, an ultralow insertion loss (IL) of <0.6 dB, and energy-efficient switching (<0.33 pJ/bit) are attainable for a 20 µm long modulator with double layer graphene. In addition, the device performs ultrafast switching with a recovery time of <600 fs, and could potentially be employed as a high-performance all-optical modulator with an ultra-high bandwidth in the hundreds of GHz. Moreover, the modulation efficiency of the device is further enhanced by stacking additional layers of graphene-hBN heterostructures, while theoretically maintaining an ultrafast response. The proposed device exhibits highly promising performance metrics, which are expected to serve the needs of next-generation photonic computing systems.