Hybrid device of hexagonal boron nitride nanoflakes with defect centres and a nano-fibre Bragg cavity

Solid-state quantum emitters coupled with a single mode fibre are of interest for photonic and quantum applications. In this context, nanofibre Bragg cavities (NFBCs), which are microcavities fabricated in an optical nanofibre, are promising devices because they can efficiently couple photons emitted from the quantum emitters to the single mode fibre. Recently, we have realized a hybrid device of an NFBC and a single colloidal CdSe/ZnS quantum dot. However, colloidal quantum dots exhibit inherent photo-bleaching. Thus, it is desired to couple an NFBC with hexagonal boron nitride (hBN) as stable quantum emitters. In this work, we realize a hybrid system of an NFBC and ensemble defect centres in hBN nanoflakes. In this experiment, we fabricate NFBCs with a quality factor of 807 and a resonant wavelength at around 573 nm, which matches well with the fluorescent wavelength of the hBN, using helium-focused ion beam (FIB) system. We also develop a manipulation system to place hBN nanoflakes on a cavity region of the NFBCs and realize a hybrid device with an NFBC. By exciting the nanoflakes via an objective lens and collecting the fluorescence through the NFBC, we observe a sharp emission peak at the resonant wavelength of the NFBC.

A Dual-Band High-Gain Subwavelength Cavity Antenna with Artificial Magnetic Conductor Metamaterial Microstructures

This paper presents dual-band high-gain subwavelength cavity antennas with artificial magnetic conductor (AMC) metamaterial microstructures. We developed an AMC metamaterial plate that can be equivalent to mu-negative metamaterials (MNMs) at two frequencies using periodic microstructure unit cells. A cavity antenna was constructed using the dual-band AMC metamaterial plate as the covering layer and utilizing a feed patch antenna with slot loading as the radiation source. The antenna was fabricated with a printed circuit board (PCB) process and measured in an anechoic chamber. The |S11| of the antenna was −26.8 dB and −23.2 dB at 3.75 GHz and 5.66 GHz, respectively, and the realized gain was 15.2 dBi and 18.8 dBi at two resonant frequencies. The thickness of the cavity, a sub-wavelength thickness cavity, was 15 mm, less than one fifth of the long resonant wavelength and less than one third of the short resonant wavelength. This new antenna has the advantages of low profile, light weight, dual-frequency capability, high gain, and easy processing.

Features of the Resonance in a Rectangular Dielectric Surace-Relief Gratings Illuminated with a Limited Cross Section Gaussian Beam

In this work the features of the resonance in a rectangular dielectric surface-relief gratings, illuminated with a limited cross-section Gaussian beam, have been studied. The rigorous coupled wave method and beam decomposition into the plane waves by the Fourier transform have been used. It is shown that there is a resonant wavelength for each thickness of the dielectric grating. The value of resonant wavelength depends on the beam angle of incidence on the gratings. Moreover, the two types of resonances can occur in the grating at certain grating parameters. The power reflection coefficient is practically equal to unity for the first type of resonance and is much smaller than unity, for the second one. The obtained results extend the knowledge regarding the nature of the waveguide resonance in the dielectric grating, considering the limited cross section beam, and they can increase its use in many applications.

Design of Visible Broadband Metamaterial Absorber Based on Metal Nickel

In this paper,we have proposed a visible broadband metamaterial absorber based on metal Nickel. The metamaterial absorber (MA) is composed of three layers,which are Nickel-based pattern array on the top, silicon dioxide in the middle layer and Nickel film at the bottom. In the whole visible spectrum(380-780nm) of our study, the average absorption of the absorber is up to 95.60%. The absorption rates at 500nm and 637nm are 96.63% and 99.93%, respectively. Also, the proposed MA is insensitive of polarization in the whole visible regime. Later, the mechanism of the absorption and the influence of the structural parameters on the absorption spectrum are investigated. Strong electrical and magnetic resonance are related to the absorption peak at the resonant wavelength. The results show the resonant wavelength of 500nm is fixed and the resonant wavelength of 637nm can be tuned by the parameters.The proposed structure will have important application prospects in the field of solar cells.

A New Design of Pressure Sensor Based on a GaAs-based Two Dimensional Photonic Crystal Slab on SiO2 Substrate

This paper reports the design and three dimensional (3D) simulation of a new photonic crystal (PC) pressure sensor. The device is constructed using a GaAs-based 2D PC slab on SiO2 substrate. The strain/stress simulations and also the spectral simulations are done using CST Studio Suite. In this investigation, the sensitivity of the proposed pressure sensor is calculated by considering the variation of the refractive index and also the deformation of the structure. The numerical results show that when pressure is applied, the refractive index variations cause an increment in the resonant wavelength of the transmission spectrum, but the deformation factor cause a decrease in the resonant wavelength. It has been shown that the relationship between the applied pressure and the resonant wavelength of the designed micro-cavity is linear. Based on the simulation results, the quality factor of the designed micro-cavity and the sensitivity of the pressure sensor are 2200 and 3.5 nm / GPa, respectively.

Hybrid Device of Hexagonal Boron Nitride Nanoflakes with Defect Centres and a Nano-Fibre Bragg Cavity

Solid-state quantum emitters coupled with a single mode fibre are of interest for photonic and quantum applications. In this context, nanofibre Bragg cavities (NFBCs), which are microcavities fabricated in an optical nanofibre, are promising devices because they can efficiently couple photons emitted from the quantum emitters to the single mode fibre. Recently, we have realized a hybrid device of an NFBC and a single colloidal CdSe/ZnS quantum dot. However, colloidal quantum dots exhibit inherent photo-bleaching. Thus, it is desired to couple an NFBC with defect centres in hexagonal boron nitride (hBN) as stable quantum emitters. In this work, we realize a hybrid system of an NFBC and defect centres in hBN nanoflakes. In this experiment, we fabricate NFBCs with a quality factor of 807 and a resonant wavelength at around 573 nm, which matches well with the fluorescent wavelength of the defect centres in hBN, using a helium focused ion beam (FIB) system. We also develop a manipulation system to place hBN nanoflakes on a cavity region of the NFBCs and realize a hybrid device with an NFBC. By exciting the nanoflakes via an objective lens and collecting the fluorescence through the NFBC, we observe a sharp emission peak at the resonant wavelength of the NFBC.