A distributed active patch antenna model of a Josephson oscillator

• Vladimir M. Krasnov

Beilstein J. Nanotechnol. 2023, 14, 151–164, doi:10.3762/bjnano.14.16

• takes into account the internal Josephson electrodynamics and allows for the determination of the effective input resistance, which couples the Josephson current to cavity modes in the transmission line formed by the junction. The model provides full characterization of Josephson oscillators and

• explains the origin of the low radiative power efficiency. Finally, I discuss the design of an optimized Josephson patch oscillator capable of reaching high efficiency and radiation power for emission into free space. Keywords: antenna theory; cavity modes; Josephson effect; terahertz radiation

• , cavity modes is one of them. Geometry is playing a decisive role for characteristics of microwave devices. Although calculations of radiative impedances of JJs do exist [33], they were not made for the FFO geometry. From the outside, the overlap JJ looks like a well-known microstrip patch antenna [34][35

Observation of collective excitation of surface plasmon resonances in large Josephson junction arrays

• Roger Cattaneo,
• Mikhail A. Galin and
• Vladimir M. Krasnov

Beilstein J. Nanotechnol. 2022, 13, 1578–1588, doi:10.3762/bjnano.13.132

• oscillating state. We use an external detector to measure the emission of electromagnetic waves. The emission power correlates with the step amplitude. Our results indicate that the emission is facilitated by the cavity modes in the electrodes. The modes are collectively excited by active junctions. In turn

• as a common external resonator, facilitating long-range phase-locking of large junction arrays with sizes larger than the emitted wavelength. Keywords: cavity modes; Josephson junctions; synchronization mechanism; THz radiation; Introduction Terahertz sources of electromagnetic waves (EMWs) in the

• collective cavity modes. Above the threshold, the amplitude of resonant steps grows in a quasi-linear manner with the number of active JJs. We employ an external microwave detector for measuring EMW emission from the arrays. It is observed that the emitted power is correlated with the amplitude of the

Coherent amplification of radiation from two phase-locked Josephson junction arrays

• Mikhail A. Galin,
• Vladimir M. Krasnov,
• Ilya A. Shereshevsky,
• Nadezhda K. Vdovicheva and
• Vladislav V. Kurin

Beilstein J. Nanotechnol. 2022, 13, 1445–1457, doi:10.3762/bjnano.13.119

• BiSCCO mesas containing up to 250 JJs [2]. A maximal emission of about 1 μW corresponds to in-phase cavity modes in the mesas, indicating the coherent superradiant nature of the emission. The arrays based on intrinsic JJs suffer from overheating, which impedes a raise of radiation power. This problem

• measurement of current–voltage characteristic (IVC) and bolometric analysis of the emitted radiation. In all cases, we observe clear signatures of inter-array interaction. They occur when both arrays are biased at the same voltage and oscillate at the same frequency, coinciding with one of the cavity modes in

• resonators (see Figure 1). In Figure 2a, we marked bias points 1–8 in array-b, at which detailed measurements are reported below for sample-1. Using the value of EM wave speed along a single-strip line obtained in [13], we can estimate the corresponding numbers of cavity modes m = 11–18. Similarly, bias

Hexagonal boron nitride: a review of the emerging material platform for single-photon sources and the spin–photon interface

• Stefania Castelletto,
• Faraz A. Inam,
• Shin-ichiro Sato and
• Alberto Boretti

Beilstein J. Nanotechnol. 2020, 11, 740–769, doi:10.3762/bjnano.11.61

Multiple Fano resonances with flexible tunablity based on symmetry-breaking resonators

• Xiao bin Ren,
• Kun Ren,
• Ying Zhang,
• Cheng guo Ming and
• Qun Han

Beilstein J. Nanotechnol. 2019, 10, 2459–2467, doi:10.3762/bjnano.10.236

• -breaking ring cavity is proposed. Discrete states are obtained in the same cavity without exciting high-order cavity modes. Because of the equal mode order, the interval of the resonant frequency is reduced. The manipulation of Fano resonances is further discussed by adjusting the degree of asymmetry. More

Geometrical optimisation of core–shell nanowire arrays for enhanced absorption in thin crystalline silicon heterojunction solar cells

• Robin Vismara,
• Olindo Isabella,
• Andrea Ingenito,
• Fai Tong Si and
• Miro Zeman

Beilstein J. Nanotechnol. 2019, 10, 322–331, doi:10.3762/bjnano.10.31

• [5][6][7][8], cavity modes [5][8][9][10][11], Fabry–Perót and whispering gallery modes [12], their characteristic high aspect ratio promotes anti-reflection, allowing for more light to be coupled into the active layer of the solar cell [13][14][15]. In addition, radial-junction nanowires have the

Cathodoluminescence as a probe of the optical properties of resonant apertures in a metallic film

• Kalpana Singh,
• Evgeniy Panchenko,
• Babak Nasr,
• Amelia Liu,
• Lukas Wesemann,
• Timothy J. Davis and
• Ann Roberts

Beilstein J. Nanotechnol. 2018, 9, 1491–1500, doi:10.3762/bjnano.9.140

• wavelength maximum in the transmission spectra, we see a spatial dependence of emission with strong enhancement near the edges of the apertures consistent with the excitation of cavity modes. At a wavelength of 860 nm (Figure 6d) we see strong emission over the central region suggesting that the excitation

Design of photonic microcavities in hexagonal boron nitride

• Sejeong Kim,
• Milos Toth and
• Igor Aharonovich

Beilstein J. Nanotechnol. 2018, 9, 102–108, doi:10.3762/bjnano.9.12

• ]. The former process is preferred when attempting to maximize the field overlap between the emitters and the cavity modes, and is often employed when using materials that are amenable to scalable nanofabrication protocols, such as gallium arsenide or silicon [17][18], and more recently diamond and

• refractive index for Q-factor calculation provides practical Q-factors. Finally, we discuss the expected Purcell enhancement due to coupling of emitters to cavity modes. Figure 4b shows the spontaneous emission rate (γsp) of a quantum emitter in the nanobeam cavity relative to an emitter in free space (γ0sp

Diamond nanophotonics

• Katja Beha,
• Helmut Fedder,
• Marco Wolfer,
• Merle C. Becker,
• Petr Siyushev,
• Mohammad Jamali,
• Anton Batalov,
• Christopher Hinz,
• Jakob Hees,
• Lutz Kirste,
• Harald Obloh,
• Etienne Gheeraert,
• Boris Naydenov,
• Ingmar Jakobi,
• Florian Dolde,
• Sébastien Pezzagna,
• Daniel Twittchen,
• Matthew Markham,
• Daniel Dregely,
• Harald Giessen,
• Jan Meijer,
• Fedor Jelezko,
• Christoph E. Nebel,
• Rudolf Bratschitsch,
• Alfred Leitenstorfer and
• Jörg Wrachtrup

Beilstein J. Nanotechnol. 2012, 3, 895–908, doi:10.3762/bjnano.3.100

• planar wavefront, light preferably couples to the symmetric fundamental mode. The entire spectrum of cavity modes is clearly visible in the photoluminescence emission with continuous-wave laser excitation of an ensemble of diamond nanocrystals at a wavelength of 532 nm (Figure 8d). The spectral positions

• ) with an ensemble of diamond nanocrystals in the spacer layer. (c) Simulated spatial cavity modes. (d) Spatio-spectrally resolved photoluminescence emission and (e) white-light transmission spectrum. Calculated spectral mode positions are indicated by vertical grey lines. (a) Normalized intensity