Optica Applicata 

About: Optica Applicata is an academic journal published by Wrocław University of Science and Technology. The journal publishes majorly in the area(s): Laser & Thin film. It has an ISSN identifier of 0078-5466. Over the lifetime, 1424 publications have been published receiving 7880 citations.

Micrometer-scale integrated silicon source of time-energy entangled photons

Abstract: Entanglement is a fundamental resource in quantum information processing Several studies have explored the integration of sources of entangled states on a silicon chip, but the devices demonstrated so far require millimeter lengths and pump powers of the order of hundreds of milliwatts to produce an appreciable photon flux, hindering their scalability and dense integration Microring resonators have been shown to be efficient sources of photon pairs, but entangled state emission has never been proven in these devices Here we report the first demonstration, to the best of our knowledge, of a microring resonator capable of emitting time-energy entangled photons We use a Franson experiment to show a violation of Bell’s inequality by more than seven standard deviations with an internal pair generation exceeding 107 Hz The source is integrated on a silicon chip, operates at milliwatt and submilliwatt pump power, emits in the telecom band, and outputs into a photonic waveguide These are all essential features of an entangled state emitter for a quantum photonic network

Laser speckle contrast imaging for measuring blood flow

Abstract: When a diffuse object is illuminated with laser light, a random interference effect known as a speckle pattern is produced. If there is movement in the object, the speckles fluctuate in intensity. These fluctuations can be used to provide information about the movement. A simple way of accessing this information is to image the speckle pattern the fluctuations cause a blurring of the speckle, leading to a reduction in the local speckle contrast. Thus velocity distributions are coded as speckle contrast variations. The same information can be obtained by using the Doppler effect, but producing a two -dimensional Doppler map requires scanning: speckle imaging provides the same information without the need to scan. This paper reviews the development of laser speckle imaging, starting with the connection established between speckle fluctuations and movement in the nineteen-seventies. In the eighties, a photographic technique for monitoring retinal blood flow was developed, and ten years later a digital version was used to monitor capillary blood flow in the skin. Today, many groups around the world are either using or researching the technique, and the paper will close by presenting some of their recent results.

Non-invasive monitoring and control in silicon photonics using CMOS integrated electronics

Abstract: As photonics moves from the single-device level toward large-scale, integrated, and complex systems on a chip, monitoring, control, and stabilization of the components become critical. We need to monitor a circuit non-invasively and apply a simple, fast, and robust feedback control. Here, we show non-invasive monitoring and feedback control of high-quality-factor silicon (Si) photonic resonators assisted by a transparent detector that is directly integrated inside the cavity. Control operations are entirely managed by a CMOS microelectronic circuit that is bridged to the Si photonic chip and hosts many parallel electronic readout channels. Advanced functionalities, such as wavelength tuning, locking, labeling, and swapping, are demonstrated. The non-invasive nature of the transparent monitor and the scalability of the CMOS readout system offer a viable solution for the control of arbitrarily reconfigurable photonic integrated circuits aggregating many components on a single chip.

Dark and singular optical solitons with competing nonlocal nonlinearities

Abstract: In this work, we study the dynamics of optical solitons in a synthetic nonlocal nonlinear media. The nonlinear dynamical model which describes the propagation of optical solitons in the weakly nonlocal nonlinear media with parabolic law nonlinearity is investigated analytically. The tool of integration that is the Riccati equation mapping approach is introduced to extract exact traveling wave solutions. As a result, an explicit dark soliton, singular soliton and periodic solutions are derived.

Adaptive optics correction of specimen-induced aberrations in single-molecule switching microscopy

Abstract: Single-molecule switching (SMS) microscopy is a super-resolution method capable of producing images with resolutions far exceeding that of the classical diffraction limit. However, like all optical microscopes, SMS microscopes are sensitive to, and often limited by, specimen-induced aberrations. Adaptive optics (AO) has proven beneficial in a range of microscopes to overcome the limitations caused by aberrations. We report here on new AO methods for SMS microscopy that enable the feedback correction of specimen-induced aberrations. The benefits are demonstrated through two-dimensional and three-dimensional STORM imaging. We expect that this advance will broaden the scope of SMS microscopy by enabling deep-cell and tissue-level imaging.