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The nanostructuring of transparent media with ultrashort laser pulses has attracted interest due to its unique applications. However, little is understood with respect to the physical mechanisms responsible for the peculiarities of the dielectrics inscribing with high intensity laser beams. It has been shown that spatio-temporal couplings (STC) inherent to the ultrashort pulses make inscribing sensitive...
In aperiodically poled quasi-phase-matching (QPM) crystals, parametric down-conversion (PDC) can generate very broadband pulsed squeezed light. This is because each part of the crystal will generate squeezed light at a different frequency [1]. But the emission will be thus inhomogeneously broadened, and one requires special measures to eliminate the chirp accompanying the pulses. This can be done...
There is a growing interest in the use of metal halide perovskites with different compositions as highly efficient light emitters among the whole visible spectral region [1]. Several groups have observed amplified spontaneous (ASE) emission in thin perovskite films. The gain and threshold values for ASE are very promising, motivating the current effort to develop practical devices that lase.
Precision spectroscopy in the mid-infrared (MIR) region is of great importance for many applications including breath diagnosis and astronomical spectroscopy as various molecular vibrational modes exist in this region. A mid-infrared comb combined with a broadband comb-resolved spectrometer can be a promising method to do this since target gas contains multiple molecular species in most applications...
Two-level coupled systems are commonly used to describe the dynamics of a variety of physical phenomena in coupled systems, such as spin ½ systems, electron population of atomic levels, coupled waveguides and more [1]. The system is usually described by two eigenmodes — symmetric and anti-symmetric, which when excited will propagate through the system unchanged. Such two-mode dynamics was also shown...
The discovery of the formation of nanogratings when irradiating fused silica glass with ultrashort laser pulses in 2003 may have opened a new generation of compact and long life time optical devices. 3D-writing, thermal stability up to 1000 oC and virtually unlimited lifetime at room temperature make optics based on nanogratings of great potential for compact sensors or devices that work in adverse...
Modulation instability (MI) refers to a process where a weak periodic perturbation of an intense continuous wave (CW) grows exponentially as a result of the interplay between dispersion and nonlinearity. In its most basic manifestation, it can be observed in homogeneous optical fibers in the anomalous dispersion regime. Another kind of MI, named parametric instability (PI), is induced by the periodic...
In this work, we present a model that describes the atomic reaction to a periodic excitation in a general case. Starting with a holeburning material, we aim at computing the steady state of the atoms of interest within the whole bulk material. This work is composed of three steps. In the first one, we generalize the optical Bloch equations to any atomic structure, keeping as long as possible the Bloch...
Up to this point, photon-entanglement sources suffered from the compromise of being either compact or efficient, but not both at the same time [1-6]. Our new concept of creating entanglement [7] combines most of the advantages of the various existing schemes. The setup offers high coupling efficiencies due to its collinear design and is still as compact and simplistic as a BBO source [1], requiring...
Bragg gratings were inscribed on the surface of thin GaN film grown on a sapphire substrate. These gratings are generated by illumination of 800 nm femtosecond pulses through a phase mask and a cylindrical lens.
Exploring new spectral bands for optical transmission is one of the solutions to support the increasingly demand of data traffic. The recent development of dedicated hollow-core photonic bandgap fibers [1], associated to the emergence of thulium doped fiber amplifiers [2] has recently focused the attention further in the infrared, and more specifically around 2 μm. Regarding integrated photonics,...
Photoinduced orientation of azobenzene chromophores in polymeric host materials has been broadly explored for holography and related diffractive optics applications [1, 2]. Illumination of the chromophore with polarized light rotates the trans isomer perpendicular to the polarization, resulting in spatially modulated birefringence. In the dark, photo-oriented chromophores thermally relax to a random...
Despite the intense developments in the field of integrated optics, there is still a need of a compact, easy and cost-effective solution for light in-coupling in integrated photonic optical waveguides for biosensing, which are designed to be single use devices in clinical environments. The majority of current solutions are based on grating couplers fabricated with e-beam lithography, which increases...
Integrated optical filters such as Bragg gratings are widely used in silicon-on-insulator technology for signal processing [1], telecommunications [2] and quantum processing [3]. Sidewall gratings offer a simple geometry that has been widely used for fabricating TE filters with high extinction ratios and accurate control over the grating stop-band and central wavelength [4]. However, a major drawback...
Interband cascade lasers (ICLs) [1, 2] combine two concepts for semiconductor lasers, in particular the long carrier lifetime of photodiodes together with the voltage-efficient cascading of the quantum cascade laser. The low threshold power makes them very attractive for mobile systems used for spectroscopy, process control or medical applications. To date no suitable overgrowth process exists for...
The use of thermally regenerated gratings for monitoring harsh environments is becoming increasingly attractive due to their thermal resilience and high precision. They are a unique type of Bragg grating created through annealing UV-laser written Fiber Bragg Gratings (FBGs) at high temperatures (above 600°C) and they have been demonstrated to operate at temperatures over 1000 °C in oxygen free environments...
Rapidly tunable, high-repetition-rate picosecond near-infrared (near-IR) optical parametric oscillators (OPOs) are of great interest for applications such as Coherent Anti-Stokes Raman Scattering microscopy [1]. Such OPOs, typically pumped in the green, pose major challenges in terms of the material damage threshold while operating at high power in combination with high repetition rates, making the...
Chirped pulse amplification (CPA), which allows the generation of extremely powerful ultrashort laser pulses in the infrared and visible spectral ranges, has recently being demonstrated for the first time on a seeded FEL in the soft X-rays [1]. The technique relies on stretching the seed pulse in time by means of a linear frequency chirp before amplification. The frequency chirp of the seed is transmitted...
Grating based fiber-chip couplers are an excellent scheme to couple between a sub-micron waveguide and an optical fiber. However, the operation bandwidth of the grating couplers is restricted to a particular wavelength band though high-coupler efficiency is achievable. An application such as Passive Optical Networks that use both O and C-band, it becomes essential to that grating couplers can be operated...
One of the most essential building blocks in modem electronics is the flip-flop. A flip-flop operates bi-stably between two states, remaining at a given output level (high or low level) until a specific input control signal changes. For many years, photonics has attempted to build all-optical flip-flops [1-3]; however, the success of these approaches has usually been limited by the dependence of the...
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