Broadband Passively Mode-Locked Fiber Laser with DNA Aqueous Solution as Saturable Absorber

We demonstrate a passively mode-locked fiber laser using aqueous DNA solution as a saturable absorber (SA), with broadband pulse laser emission from 1 to 1.5 µm. The mode-locked laser with erbium-doped fiber as the gain material has a center wavelength of 1563 nm, a 3 dB bandwidth of 3.9 nm, and a pulse width of 822 fs, whereas the laser with ytterbium-doped fiber as the gain material and an identical DNA aqueous SA has a center wavelength of 1037 nm, a 3 dB bandwidth of 5.04 nm, and a pulse width of 250 ps. The proposed laser, which is simple and cost effective to fabricate, exhibits excellent long-term stability as well as thermal stability during high-power operation. This mode-locked laser scheme with a liquid-phase DNA component has the potential to provide in-depth understanding of the optical nonlinearity and usefulness of DNA.

Influence of COVID-19 Pandemic Lockdown on Patients from the Bariatric Surgery Waiting List

Background and Objectives: Social isolation and lockdown due to the COVID-19 pandemic have influenced dietary habits and physical activity of all the population, but the obese population is the most vulnerable to weight gain. Material and Methods: A group of 189 patients (166 female and 23 male) from the bariatric surgery waiting list filled in a survey about the influence of COVID-19 pandemic lockdown on their dietary habits, physical activity, and the possibility of contact with their bariatric care center. Results: The majority of patients with weight gain declared a decrease in physical activity, compared to half of the patients without weight gain (50.5% vs. 74.5%, p < 0.05). The continuation of bariatric care and the possibility of contact with a bariatric surgeon, dietician, and psychologist had each significant influence on reducing the risk of patients’ weight gain (p < 0.05). Conclusions: Maintaining physical activity and contact with bariatric care specialists are important factors in allowing to avoid weight gain in patients waiting for bariatric surgery.

Nonreciprocal transmission in a parity-time symmetry system with two types of defects

In this paper, we have studied two different mechanisms of nonreciprocal and asymmetric transmission in the one-dimensional asymmetric optical system composed of parity-time (PT) and magneto-optical materials with different defect layers. It is shown that there are three pairs of nonreciprocal dispersive curves with the perfect transmission in the three different band gaps, when the defect layer is filled with normal material. When the defect layer is filled with magneto-optical material, the transmittivity of two nonreciprocal frequencies can be modulated by the magnitude and direction of the defect layer’s external magnetic field and appears to be asymmetric nonreciprocal transmission. One-way frequency corresponding to one direction has extraordinary transmission, and the other one-way frequency corresponding to the opposite direction is suppressed. When the defect layer is filled with loss or gain material, the transmittivity of two nonreciprocal frequencies can be amplificated or attenuated simultaneously, respectively. The nonreciprocal propagation is originated from the resonant modes in the system due to the defect layer, and the nonreciprocal and asymmetric transmission is determined by the broken PT system due to magneto-optical and gain/loss material in the defect layer. Such controllable and asymmetric nonreciprocal propagation in the composite system may have broad potential applications in nonreciprocal communication and integration devices.

In-Plane Monolithic Integration of Scaled III-V Photonic Devices

It is a long-standing goal to leverage silicon photonics through the combination of a low-cost advanced silicon platform with III-V-based active gain material. The monolithic integration of the III-V material is ultimately desirable for scalable integrated circuits but inherently challenging due to the large lattice and thermal mismatch with Si. Here, we briefly review different approaches to monolithic III-V integration while focusing on discussing the results achieved using an integration technique called template-assisted selective epitaxy (TASE), which provides some unique opportunities compared to existing state-of-the-art approaches. This method relies on the selective replacement of a prepatterned silicon structure with III-V material and thereby achieves the self-aligned in-plane monolithic integration of III-Vs on silicon. In our group, we have realized several embodiments of TASE for different applications; here, we will focus specifically on in-plane integrated photonic structures due to the ease with which these can be coupled to SOI waveguides and the inherent in-plane doping orientation, which is beneficial to waveguide-coupled architectures. In particular, we will discuss light emitters based on hybrid III-V/Si photonic crystal structures and high-speed InGaAs detectors, both covering the entire telecom wavelength spectral range. This opens a new path towards the realization of fully integrated, densely packed, and scalable photonic integrated circuits.

Lithographic in-mold patterning for CsPbBr3 nanocrystals distributed Bragg reflector single-mode laser

A newly developed lithographic in-mold patterning process is proposed to fabricate on-chip single-mode distributed-Bragg-reflector waveguide small lasers that utilized CsPbBr3 perovskite nanocrystals as the gain material.

Migrant Cine-Eye: Storytelling in Documentary and Participatory Filmmaking

The so-called European ‘refugee crisis’ has bred a profusion of audiovisual accounts throughout the region, many of which aimed to give voice to hitherto voiceless, uprooted people. But as many of these ‘untold stories’ gain material expression as storylines, we are urged to consider the implications of yet another form of displacement: from the historical person to the film character, from personal stories to media representations. The growing interest into the migrant issue and visual representations of refugees have played an important role in the public construction of the ‘crisis’ but have also, paradoxically, obscured or silenced migrant voices. The authors of this paper, a documentary filmmaker (Trencsényi) and a social anthropologist (Naumescu) seek to explore narrative strategies and ethics of representation in European documentaries made after 2010 as well as their participatory filmmaking project developed in the wake of the 2015 refugee crisis in Hungary. Having collaborated on several documentary films and filmmaking workshops, they approach this issue from the perspective of practitioners, offering a critical reflection as well as possible strategies for those aiming to produce audiovisual works in this field. The inclusion of refugees’ insight and their ways of constructing their own stories as well as their own observations on the receiving societies can open new possibilities for collaboration and creative engagement for social scientists and filmmakers preparing visual fieldnotes, ethnographic and documentary films as well as participatory projects.

Micro and Nano Raman Lasers

Raman lasers (RLs) are a class of optically pumped laser, offering coherent lights at any desired wavelength by a proper choice of the pump wavelength, when both wavelengths are within the transparency region of the gain material and an adequately high nonlinearity and/or optical intensity are provided [...]

Locating civil society in Marx and Gramsci

This chapter explores the origins and aims of the two phases of the WISERD; research programme on civil society. It examines the first phase research agenda and some research results on: locality, community and civil society; individuals, institutions and governance; economic austerity, social enterprise and inequality; generation, life course and social participation. It also outlines the second phase concern with frontiers of civic exclusion and expansion; polarization, austerity and civic deficit; contentious politics of civic gain; material resources, social innovations and civil repair; and data infrastructure and data integration. The influence of David Lockwood’s account of civic stratification is also explored.