Amira Baili

Design and analysis of equiangular spiral photonic crystal fiber for mid-infrared supercontinuum generation

A design of equiangular spiral photonic crystal fiber (PCF) in As2Se3 chalcogenide glass is reported for mid-infrared supercontinuum generation. Supercontinuum covering the 1.2–15 μm molecular fingerprint region is achieved using only 8 mm long designed PCF pumped with 50 fs laser pulses of 500 W peak power. The structural parameters have been tailored for all-normal dispersion characteristic. Proposed structure has high nonlinearity (γ = 12474 W−1 km−1) at 3.5 μm with very low and flat dispersion −2.9 [ps/(nm × km)]. Supercontinuum with such broadening and high coherence degree is applicable for mid-infrared spectroscopy, gas sensing, early cancer diagnostics and free space communication.

Maximizing the bandwidth of coherent, mid-IR supercontinuum using highly nonlinear aperiodic nanofibers

We describe in detail a new procedure of maximizing the bandwidth of mid-infrared (mid-IR) supercontinuum (SC) in highly nonlinear microstructured As2Se3 and tellurite aperiodic nanofibers. By introducing aperiodic rings of first and secondary air holes into the cross-sections of our microstructured fiber designs, we achieve flattened and all-normal dispersion profiles over much broader bandwidths than would be possible with simple periodic designs. These fiber designs are optimized for efficient, broadband, and coherent SC generation in the mid-IR spectral region. Numerical simulations show that these designs enable the generation of a SC spanning over 2290 nm extending from 1140 to 3430 nm in 8 cm length of tellurite nanofiber with input energy of E = 200 pJ and a SC bandwidth of over 4700 nm extending from 1795 to 6525 nm generated in only 8 mm-length of As2Se3-based nanofiber with input energy as low as E = 100 pJ. This work provides a new type of broadband mid-IR SC source with flat spectral shape as well as excellent coherence and temporal properties by using aperiodic nanofibers with all-normal dispersion suitable for applications in ultrafast science, metrology, coherent control, non-destructive testing, spectroscopy, and optical coherence tomography in the mid-IR region.

New design of As2Se3-based chalcogenide photonic crystal fiber for ultra-broadband, coherent, mid-IR supercontinuum generation

In this paper, we propose a new design of all-normal and ultra-flat dispersion As2Se3-based chalcogenide photonic crystal fibers (PCF). The generation of supercontinuum (SC) in the designed fibers is investigated, which has flat and smooth profile, covers a broad range extending from 2 to 8 μm. The significance of this work is that it provides a new type of mid-infrared SC source with flat shape, broadband and high coherence properties by pumping the As2Se3-based PCF. Thus many applications can be performed such as fiber lasers, pulse compression and multi-wavelength optical sources in the mid-infrared region.

Two octaves spanning supercontinuum in highly nonlinear As2Se3 nanophotonic crystal fiber for midinfrared applications

Abstract. A new design of all-normal and near-zero flattened dispersion based on chalcogenide nanophotonic crystal fiber (PCF) has been proposed to generate smooth and ultra-broadband supercontinuum (SC) in the midinfrared (IR) region. With the optimized geometric parameters, the As2Se3 nano-PCF has been found to be suitable for two-octave supercontinuum generation (SCG). We designed a nano-PCF having a flat top dispersion curve with a maximum value of −2.3 [ps/(nm km)] and a large nonlinear coefficient equal to 7250 (W km)−1 around the wavelength of 5.24  μm. By numerical simulations, we predict the generation of a very broadband SC in the mid-IR region extending from 2 to 10  μm in only 2-mm fiber lengths by using a femtosecond laser having a full-width at half-maximum of 50 fs and a relatively low energy of E=80  pJ. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-IR spectral region has potential usefulness in a variety of applications requiring a broad and mid-IR spectrum, such as WDM sources, fiber sensing, IR spectroscopy, fiber laser, and optical tomography coherence.

Design of single-polarization single-mode photonic nanowire

A novel design of single polarization single mode (SPSM) photonic nanowire is proposed. Using a cladding structure with circular air holes, a new design of a photonic nanowire with ultra-wideband range of 740 nm for SPSM operation is obtained. The numerical results show that the SPSM-nanowire is low-loss within the wavelengths ranging from 1.17 μm to 1.91 μm, the confinement loss of the slow-axis mode is less than 0.15 dB/km and the fast-axis mode is unguided. This fiber has greater advantages in polarization sensitive applications, such as fiber optic gyroscopes, fiber optic current sensors, high-power fiber lasers, and coherent optical communications.

Multimode Brillouin spectrum in dual core chalcogenide photonic nanofiber for sensing applications (Withdrawal Notice)

This paper, originally published on September 7, 2016, was withdrawn from the SPIE Digital Library on October 24, 2016, at the request of the authors.

Slow light generated via Brillouin scattering in small core chalcogenide photonic crystal fiber

In this paper, we have calculated the highly efficient generation of the slow light based on the Stimulated Brillouin scattering (SBS) in a small core As2Se3 chalcogenide PCF. A Brillouin gain coefficient, gB. of 9.05 10-9 m.W-1 is found around the acoustic frequency of 8.08 GHz in small core diameter of 1.69 μm with 1.5 μm2 effective mode area at 1550 nm. A Brillouin gain of 77.3 dB was achieved with only 10 mW pump power in a 10-m fiber length, which leads to the optical time delay of 94 ns. In terms of the proposed figure of merit, it shows 2.77 dB/mW/m which is about 110 times more efficient than conventional single-mode fibers. These fibers are expected to have potential applications in realization of compact slow light devices.

New design of multicore nonlinear photonic crystal fiber for mid-IR supercontinuum generation

Supercontinuum (SC) generation in six core hexagonal lattice photonic crystal fiber (PCF) made of As2Se3-based chalcogenide glass was numerically investigated. The fiber was excited by 50 fs input pulse with hyperbolic secant field profile with tunability range of 2.5-5.5 μm. We obtained a flat-top normal dispersion profile when choosing Λ=1 μm and d=0.9 μm. By pumping near the zero dispersion wavelength, a high coherent SC spanning over 4 μm was generated with a launched pulse energy of E= 100 pJ in only 1 cm fiber length. The generated SC is therefore ideal for applications in ultrafast science, metrology, coherent control, non-destructive testing, spectroscopy, and optical coherence tomography in the mid-infrared region.

Design of equiangular spiral photonic crystal fiber for supercontinuum generation at 1550 nm

An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has been presented. The structure parameters have been tailored for zero dispersion wavelength (ZDW) at λZDW=1570 nm. The fiber structure has high nonlinearity (γ = 2000 w-1 Km-1) at 1550 nm wavelength with very low and flat dispersion -0.152 [ps/(nm×km)]. We have generated supercontinuum using only 2 mm length of tellurite ES PCF with low input pulse energy of 200 pJ by pumping at 1550 nm. The proposed fiber may be a suitable candidate for nonlinear applications.

2-10 μm supercontinuum broadening using a highly nonlinear chalcogenide microfiber for mid-IR applications

A new design of the As2Se3 microfiber has been presented. With the optimized geometric parameters: pitch Λ= 0.8 μm and five different air filling ratios varying from 0.4 to 0.95, the structure exhibits an all normal dispersion with a flat top equal to -2.3 [ps/(nm.km)], a confinement loss less than 10-2 dB/km, and a large nonlinear coefficient equal to 7250 (w. km)-1. Using the generalized nonlinear Schrödinger equation, we generate a very broadband supercontinuum (SC) in the mid-infrared region. By pumping the fiber at λp=5.24 μm with a femtosecond laser having 50 fs as a width with a relatively low energy of E=80 pJ, we generate a large spectrum extending from 2 μm to 10 μm in only 2 mm fiber length. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-infrared (IR) spectral region have potential usefulness in a variety of applications requiring a broad mid-IR spectrum such as fiber sensing, IR spectroscopy, fiber laser, optical tomography coherence.