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It was shown that the spectral width of a nominally continuous wave Raman fiber laser (RFL) output becomes narrower after propagation in normal dispersion (β2>0) fiber [1]. This feature, attributed to Inverse Four-Wave Mixing (IFWM), was especially pronounced when the RFL output had a double-peak spectral shape caused by efficient FWM inside the cavity [2]. This spectrum was transformed into a...
Antiresonant hollow core fibers (ARHCF) have low propagation loss, broad transparency windows from ultraviolet to mid-infrared regime in fundamental mode propagation and can be easily fabricated [1, 2]. In these fibers, geometrically-induced strand resonances are given by λm = 2t√n2 −1/m, where t is the strand thickness, n is the refractive index of the material and m is the integer resonance. The...
Since the free-electron laser FLASH at DESY in Hamburg, Germany [1] lases in Self-Amplified Spontaneous Emission (SASE) mode each pulse is “unique” and has different pulse energy, XUV spectrum and pulse duration. Due to very small fluctuations in the acceleration, the arrival time of the XUV pulses jitters within several tens of femtoseconds. A Terahertz (THz) field driven streak camera [2,3] has...
The study of the evolution of quantum states performed with photonic techniques, commonly requires the use of complex interferometric schemes [1]. Here we present a novel setup based on multipass bulk interference that allows to recreate and measure different kinds of quantum state evolutions, passing from sequential maps to quantum walks.
The latest advances in the design and implementation of semiconductor sources of quantum light show their competence to efficiently deliver indistingishable single photons [1-3] or photon pairs with high degree of entanglement [4-5]. These achievements combined with the possibility of photon storage [6] show the potential of quantum dots to become building blocks of a quantum network.
Quantum interference forces two indistinguishable input photons to depart a beamsplitter in the same (of two possible) spatial output modes; this is known as the Hong-Ou-Mandel (HOM) effect. It provides a quantitative way of measuring the distinguishability between two photons and also has been utilised to determine their relative temporal delays [1, 2]. HOM interferometry offers numerous advantages...
It is commonly understood that, to cast light into a state with sub-Poissonian statistics, a strong optical nonlinearity is needed. The most common examples are resonance fluorescence of a two-level system, or a Kerr medium where the Kerr energy per photon U is much larger than the optical linewidth κ. In both cases, a single-photon nonlinearity is realized, whereby the presence of a single photon...
Slow light has been explored for building quantum networks, with particular interest in slowing the group velocity of single photons [1], and more recently exploited to enhance the measurement of small phase shifts. Generally, slow-light effects have been characterized as the net effect of a pulse propagating through the slow-light medium, i.e., as a pulse delay time Δt measured with a fast photodiode...
We report the new method for the measurement of the phase-relaxation time T2 of a medium with femtosecond time resolution. The method is based on the effect of quantum interference of entangled photons and does not require the actual use of a femtosecond light source. The method provides the practical and cost-efficient alternative to existing methods of ultrafast time-resolved spectroscopy [1].
Accurate modelling of photonic systems has to allow for the treatment of complex geometries and unusual material properties. While the former suggests the use of unstructured measures in conjunction with high-order basis functions such as in traditional finite element approaches, the latter implies working within the time domain so that general nonlinearities and transient phenomena can be considered...
Optics and photonics are key enabling technologies of the 21st century offering great potential for new applications in fields as diverse as medicine, environmental and prognostic structural health monitoring or aeronautics, among others. Many of these applications require the implementation of highly-functional optical sensor networks ideally realized by using cost-efficient materials with tailored...
As new generations of diverse polymer materials become available [1], these are being used for an increasingly diverse variety of applications in optics, thereby allowing the realization of entirely new kinds of optical components and systems. Using manufacturing technologies based on MEMS and microsystems, flexible and stretchable materials may be used for the fabrication of components as diverse...
Due to their low-cost, comparable transparency and ease of preparation, polymers are widely used to fabricate various micro- and nano-structures for their applications in micro-optics, micro-fluidics, biomedical systems and so on. And in recent years, femtosecond (fs) laser direct writing process has become a popular tool to fabricate arbitrary three-dimensional (3D) microstructures with nanometer...
Direct laser writing (DLW) is a powerful tool toward the development of ultimate three-dimensional (3D) photonic devices. Because of the increasing demand for realising nano-geometries, the diffraction-limited resolution associated with DLW should be overcome to access the nanoscale. To meet this challenge, the concept of 3D nano printing, which is called super-resolution photoinduction-inhibition...
In the early 1950s, Fermi, Pasta and Ulam (FPU) published a seminal report in which they numerically investigated the dynamics of a one-dimensional anharmonic chains of particles [1]. They argued that, owing to the nonlinear coupling, the system would irreversibly relax to a state of thermal equilibrium, in which the energy is equidistributed among all modes. Instead of such a thermalization process,...
When light propagates in a turbid medium, multiple scattering prevents it from reaching depths much greater than the mean free path. This limited propagation presents a problem for many fields where optical energy delivery through scattering media is critical, such as energy conversion in dye-sensitized solar cells, light-based medical techniques, or white LEDs. In this work we show that wavefront...
Owing to their wide range of exceptional properties, two-dimensional (2D) materials have emerged as exciting media for the development of highly functional optoelectronic devices. Of these materials, the transition-metal dichalcogenides (TMDCs) are of particular interest as, unlike graphene, they are often semiconductors, and their optoelectronic properties can be tuned quite dramatically by controlling...
Hardware-accelerated electromagnetic solver tools have been known for some time [1], but due to developments in web scripting languages, they can now be widely delivered via web-browsers. The use of webbrowsers for delivery is advantageous in educational settings such as distance learning, because the students lose no time to the potential inconvenience of downloading and installing native software...
One of the cornerstones of quantum mechanics is that matter can possess both particle- and wave-like properties. Since the inception of quantum mechanics, such wavelike behaviour has been observed in ever more massive systems — ranging from electrons, neutrons, ultracold atoms, and even large molecules comprising many hundreds of atoms. An exciting route to further extend the exploration of quantum...
Photoacoustic microscopy (PAM) is a promising imaging modality that combines optical and ultrasound imaging. It combines the advantages of high ultrasonic spatial resolution and high optical contrast. When a short laser pulse illuminates the tissue, absorbed light leads to an acoustic emission via thermoelastic expansion [1]. The laser system needs to generate short enough pulses, i.e., several nanoseconds,...
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