We investigate waveguide-integrated plasmonic graphene photodetector operating based on the hot carrier photo-bolometric effect, which is characterized simultaneously by high responsivity on the scale of hundreds of AW-1 and high speed on the scale of 100s of GHz. We develop a theory of bolometric effect originating from the band nonparabolicity of graphene and estimate responsivity due to bolometric effect is shown to significantly surpass the responsivity of co-existing photo-conductive effect thus convincingly demonstrating the dominance of bolometric effect. Based on the theory we propose a novel detector configuration based on hybrid waveguide that allows for efficient absorption in the graphene over short distance and subsequently a large change of conductivity. The results demonstrate the potential of graphene for high-speed communication systems.
We appraise a waveguide-integrated plasmonic graphene photodetector based on the hot carrier photo-bolometric effect, with performance characterized simultaneously by high responsivity, on the scale of hundreds of AW-1, and high speed on the scale of 100s of GHz. Performance evaluation is based on a theory of bolometric effect originating from the band nonparabolicity of graphene. Results compare favorably with the state-of-the-art plasmonic bolometric photodetectors, predicting up to two orders of magnitude increase in a responsivity while keeping speed on the same level, defined by the elect…
We present a micrometer scale, on-chip integrated, plasmonic enhanced graphene photodetector (GPD) for telecom wavelengths operating at zero dark current. The GPD is designed and optimized to directly generate a photovoltage and has an external responsivity~12.2V/W with a 3dB bandwidth~42GHz. We utilize Au split-gates with a$\sim$100nm gap to electrostatically create a p-n-junction and simultaneously guide a surface plasmon polariton gap-mode. This increases light-graphene interaction and optical absorption and results in an increased electronic temperature and steeper temperature gradient acr…
We propose an on-chip CMOS compatible graphene plasmonic photodetector based on the photo-thermoelectric effect (PTE) that occurs across an entire homogeneous graphene channel. The proposed photodetector incorporates the long-range dielectric-loaded surface plasmon polariton (LR-DLSPP) waveguide with a metal stripe serving simultaneously as a plasmon supporting metallic material and one of the metal electrodes. Large in-plane component of the transverse magnetic (TM) plasmonic mode can couple efficiently to the graphene causing large temperature increases across an entire graphene channel with…
Graphene-based photodetectors, taking advantage of high carrier mobility and broadband absorption in graphene, have recently experienced rapid development. However, their performances with respect to the responsivity and bandwidth are still limited by either weak light-graphene interaction or large resistance-capacitance product. Here, we demonstrate a waveguide coupled integrated graphene plasmonic photodetector on the silicon-on-insulator platform. Benefiting from plasmonic enhanced graphene-light interactions and subwavelength confinement of the optical energy, we present a small-footprint …
Metamaterials have recently established a new paradigm for enhanced light absorption in state-of-the-art photodetectors. Here, we demonstrate broadband, highly efficient, polarization-insensitive, and gate-tunable photodetection at room temperature in a novel metadevice based on gold/graphene Sierpinski carpet plasmonic fractals. We observed an unprecedented internal quantum efficiency up to 100% from the near-infrared to the visible range with an upper bound of optical detectivity of $10^{11}$ Jones and a gain up to $10^{6}$, which is a fingerprint of multiple hot carriers photogenerated in g…
Here, we propose titanium nitride (TiN) as an alternative plasmonic material for an on-chip silicon plasmonic Schottky photodetector that is based on an internal photoemission process and operating at telecom wavelengths. The examined structure employs an asymmetric metal-semiconductor-metal waveguide structure with one of the electrodes being gold and the second either gold, titanium or titanium nitride. Apart from the excellent optical properties desired for this type of photodetector such as high absorption losses and reasonably high real part of the permittivity, titanium nitride is a CMOS…
Graphene has shown great potentials for high-speed photodetection. Yet, the responsivities of graphene-based high-speed photodetectors are commonly limited by the weak effective absorption of atomically thin graphene. Here, we propose and experimentally demonstrate a plasmonically enhanced waveguide-integrated graphene photodetector. The device which combines a 6 micron long layer of graphene with field-enhancing nano-sized metallic structures, demonstrates a high external responsivity of 0.5 A/W and a fast photoresponse way beyond 110 GHz. The high efficiency and fast response of the device e…
Visible and infrared photons can be detected with a broadband response via the internal photoeffect. By using plasmonic nanostructures, i.e. nanoantennas, wavelength selectivity can be introduced to such detectors through geometry-dependent resonances. Also, additional functionality, like electronic responsivity switching and polarization detection have been realized. However, previous devices consisted of large arrays of nanostructures to achieve detectable photocurrents. Here we show that this concept can be scaled down to a single antenna level, resulting in detector dimensions well below t…
Graphene has extraordinary electro-optic properties and is therefore a promising candidate for monolithic photonic devices such as photodetectors. However, the integration of this atom-thin layer material with bulky photonic components usually results in a weak light-graphene interaction leading to large device lengths limiting electro-optic performance. In contrast, here we demonstrate a plasmonic slot graphene photodetector on silicon-on-insulator platform with high-responsivity given the 5 um-short device length. We observe that the maximum photocurrent, and hence the highest responsivity, …
Here we propose a waveguide-integrated germanium plasmonic photodetector that is based on a long-range dielectric-loaded surface plasmon polariton waveguide configuration. As this configuration ensures a long propagation distance, i.e., small absorption into metal, and a good mode field confinement, i.e., high interaction of the electric field with a germanium material, it is perfect for a realization of plasmonic germanium photodetectors. Such a photodetector even without optimization provides a responsivity exceeding 1 A/W for both wavelengths of 1310 nm and 1550 nm. To achieve such a respon…
Deep understanding of plasmonic nanoparticles (PNPs)-light interaction over semiconductors surface shows great promises in enhancing their optoelectronic devices efficiency beyond the conventional limit. However, PNP-light interaction critically decided by the distribution density of PNPs over the semiconductor surface which is not entirely understood. Here, a systematic study depicting how the interparticle gap between Silver (Ag) NPs influences the performance of the \b{eta}-Ga2O3 based solar-blind photodetector. Interestingly, a remarkable transition is observed, where the varied interparti…
A fast silicon-graphene hybrid plasmonic waveguide photodetectors beyond 1.55 μm is proposed and realized by introducing an ultra-thin wide silicon-on-insulator ridge core region with a narrow metal cap. With this novel design, the light absorption in graphene is enhanced while the metal absorption loss is reduced simultaneously, which helps greatly improve the responsivity as well as shorten the absorption region for achieving fast responses. Furthermore, metal-graphene-metal sandwiched electrodes are introduced to reduce the metal-graphene contact resistance, which is also helpful for improv…
Plasmonic Particle Integration into Near-Infrared Photodetectors and Photoactivated Gas Sensors: Towards Sustainable Next-Generation Ubiquitous Sensing
Photo-bolometric effect is critically important in optoelectronic structures and devices employing metallic electrodes with nanoscale features due to heating caused by the plasmonic field enhancement. One peculiar case is individual silver nanowires (Ag NWs) and their networks. Ag NW-networks exhibit excellent thermal, electrical, and mechanical properties, providing a simple yet reliable alternative to common flexible transparent electrode materials used in optoelectronic devices. To date there have been no reports on the photoresponse of Ag NWs. In this work, we show that a single Ag NW and …
Plasmon excitations in metallic nanostructures can decay directly into dynamic electron-hole pairs (EHPs), exploitable for photocurrent generation. This approach has extensively been employed to develop nanoplasmonic light-sensing devices with significant responsivity and quantum efficiency. Of particular interest is infrared plasmonic photodetectors with a wide range of technological applications, including spectroscopy, biosensing, and surveillance. This Review discusses fundamentals, recent advances, and trending mechanisms in the understanding and applications of plasmon-enhanced photocurr…
Integrating and manipulating the nano-optoelectronic properties of Van der Waals heterostructures can enable unprecedented platforms for photodetection and sensing. The main challenge of infrared photodetectors is to funnel the light into a small nanoscale active area and efficiently convert it into an electrical signal. Here, we overcome all of those challenges in one device, by efficient coupling of a plasmonic antenna to hyperbolic phonon-polaritons in hexagonal-BN to highly concentrate mid-infrared light into a graphene pn-junction. We balance the interplay of the absorption, electrical an…
Free-space circularly polarized light (CPL) detection, requiring polarizers and waveplates, has been well established, while such spatial degree of freedom is unfortunately absent in integrated on-chip optoelectronics. So far, those reported filterless CPL photodetectors suffer from the intrinsic small discrimination ratio, vulnerability to the non-CPL field components, and low responsivity. Here, we report a distinct paradigm of geometric photodetectors in mid-infrared exhibiting colossal discrimination ratio, close-to-perfect CPL-specific response, a zero-bias responsivity of 392 V/W at room…
Graphene has emerged as an ultrafast optoelectronic material for on-chip photodetector applications. The 2D nature of graphene enables its facile integration with complementary metal-oxide semiconductor (CMOS) microelectronics and silicon photonics, yet graphene absorbs only $\sim$2.3% of light. Plasmonic metals can enhance the responsivity of graphene photodetectors, but may result in CMOS-incompatible devices, depending on the choice of metal. Here, we propose a plasmon-enhanced photothermoelectric graphene detector using CMOS-compatible titanium nitride (TiN) on the silicon-on-insulator (SO…
On-chip manipulating and controlling the temporal and spatial evolution of light is of crucial importance for information processing in future planar integrated nanophotonics. The spin and orbital angular momentum of light, which can be treated independently in classical macroscopic geometrical optics, appear to be coupled on subwavelength scales. We use spin-orbit interactions in a plasmonic achiral nano-coupler to unidirectionally excite surface plasmon polariton modes propagating in seamlessly integrated plasmonic slot waveguides. The spin-dependent flow of light in the proposed nanophotoni…
Integrating two-dimensional (2D) crystals into optical fibers can grant them optoelectronic properties and extend their range of applications. However, our ability to produce complicated structures is limited by the challenges of chemical vapor deposition (CVD) manufacturing. Here, we successfully demonstrate a 2D-material heterostructure created on a fiber endface by integrating a microscale multilayer graphene-MoS2-WS2 van der Waals (vdW) heterostructure film on it. Hence, based on simple layer-by-layer transferring, a visible-to-infrared gating-free all-in-fiber photodetector (FPD) is produ…
We report compact, scalable, high-performance, waveguide integrated graphene-based photodetectors (GPDs) for telecom and datacom applications, not affected by dark current. To exploit the photothermoelectric (PTE) effect, our devices rely on a graphene-polymer-graphene stack with static top split gates. The polymeric dielectric, poly(vinyl alcohol) (PVA), allows us to preserve graphene quality and to generate a controllable p-n junction. Both graphene layers are fabricated using aligned single-crystal graphene arrays grown by chemical vapor deposition. The use of PVA yields a low charge inhomo…
This study demonstrates a rapid, wash-free dip-type fiber optic plasmonic sandwich (DiP) assay capable of zeptomole analyte detection and 6-orders of wide dynamic range. The DiP assay is realized on a compact U-bent fiber optic probe surface by dipping the antibody functionalized probe into a mixture of sample solution and AuNP labeled reagent. U-bent fiberoptic probes with a high evanescent wave absorbance sensitivity allow detection of the high extinction gold nanoparticle (AuNP) labels in terms of a drop in the light intensity, which is measured with the help of a pair of LED and photodetec…
The challenge of next generation datacom and telecom communication is to increase the available bandwidth while reducing the size, cost and power consumption of photonic integrated circuits. Silicon (Si) photonics has emerged as a viable solution to reach these objectives. Graphene, a single-atom thick layer of carbon5, has been recently proposed to be integrated with Si photonics because of its very high mobility, fast carrier dynamics and ultra-broadband optical properties. Here, we focus on graphene photodetectors for high speed datacom and telecom applications. High speed graphene photodet…
Room temperature operation is mandatory for any optoelectronics technology which aims to provide low-cost compact systems for widespread applications. In recent years, an important technological effort in this direction has been made in bolometric detection for thermal imaging$^1$, which has delivered relatively high sensitivity and video rate performance ($\sim$ 60 Hz). However, room temperature operation is still beyond reach for semiconductor photodetectors in the 8-12 $μ$m wavelength band$^2$, and all developments for applications such as imaging, environmental remote sensing and laser-bas…
Magnetometers based on quantum mechanical processes enable high sensitivity and long-term stability without the need for re-calibration, but their integration into fieldable devices remains challenging. This paper presents a CMOS quantum vector-field magnetometer that miniaturizes the conventional quantum sensing platforms using nitrogen-vacancy (NV) centers in diamond. By integrating key components for spin control and readout, the chip performs magnetometry through optically detected magnetic resonance (ODMR) through a diamond slab attached to a custom CMOS chip. The ODMR control is highly u…
