Fiber For Mid-infrared Supercontinuum Generation Research Articles

Optimization of dispersions in benzene-core square photonic crystal fibers for mid-infrared supercontinuum generation with very low peak power

An ultra-broadband, very low peak power supercontinuum source is proposed based on a novel benzene-filled structured photonic crystal fiber. The modification of the structural parameters has been highly effective in improving dispersion properties, an ultra-flat all-normal dispersion is achieved with fluctuations of ±1.174 ps/(nm.km) in the 0.458 µm wavelength region. Three fibers with suitable optical properties best meet the requirements of supercontinuum generations with low peak power based on numerical simulation results. With anomalous dispersion regime, the first fiber offers the supercontinuum spectra in the mid-infrared region spanning from 0.784 µm to 3.973 µm (2.539 µm bandwidth at 30 dB) using laser pulses excited at 1.55 µm has a peak power of 150 W. A pulse with a peak power of 280 W propagates in a 5 cm length of the second fiber results in a supercontinuum spectrum covering from 0.744 µm to 1.859 (bandwidth 1.063 µm at 30 dB) at a pump wavelength of 1.3 µm with all-normal dispersion regime. A smooth, highly coherent supercontinuum spectrum spanning from 0.843 µm to 2.517 µm (bandwidth at 30 dB of 1.608 µm) is achieved when the third fiber has all-normal ultra-flat dispersion profile pumped at 1.75 µm wavelength with laser pulse peak power of 350 W. With very low peak power, these proposed three-fiber based broadband supercontinuum sources could be a low-cost alternative to traditional glass-core fiber, which has great potential for mid-infrared spectroscopy.

A dehydrated W-type fluorotellurite fiber for mid-infrared supercontinuum generation

A W-type fluorotellurite glass fiber was fabricated by rotational casting method. The OH absorption coefficient of the fluorotellurite glass is 0.004 cm−1, and the OH-induced attenuation of the fiber is 8.5 dB/m at 3.1 μm. The fiber has a small core of 5 μm in diameter with the lowest loss of 0.9 dB/m at 2.7 μm. 1–2.4 µm supercontinuum (SC) has been generated from a 30 cm-long dehydrated fluorotellurite glass fiber pumped by a 1560 nm femtosecond fiber laser. The numerical simulation is in good agreement with experiment result based on the generalized nonlinear Schrödinger equation. The experiment and numerical simulation show that the dehydrated fluorotellurite fiber is a promising candidate for SC in 1–4 µm region.

Semiconductor material photonic crystal fiber for mid-infrared supercontinuum generation

In this paper, Al0.24Ga0.76As based holey optical fiber is designed for coherent supercontinuum generation. It is mainly simulated for optical characteristic of lattice microstructures. For computational studies, the introduced design is composed of five loops of air vents with circular and elliptical structures. Flat and anomalous dispersion in the mid-infrared range has been achieved by obtaining a high nonlinear Kerr coefficient 5402 W−1 km−1 at the pump wavelength of 3.25 µm from the proposed microstructure fiber. Thereby, the expansion of the supercontinuum spectrum from 1.70 µm to 8.5 µm has been obtained. With the help of the high effective refractive index at the pump wavelength and the small effective mode region, proper supercontinuum spectrum (SC) is generated. The range of the spectrum of supercontinuum based on fiber length, pump duration and pump energy is simulated. Applications of this work will be advantageous in bio-medical, optical sensing, and wavelength conversion.

Design of a novel star type photonic crystal fiber for mid-infrared supercontinuum generation

In this work, we have designed two simple photonic crystal fibers (PCFs) with the highly nonlinear chalcogenide material of Ge11.5As24Se64.5 for broadband mid-infrared supercontinuum generation. The hexagonal lattice of air holes in a star type arrangement has been considered in the designs, where only two different air hole sizes and a constant pitch are employed. The study shows that the diameter of the air hole has significant influence on both the dispersion and the nonlinearity parameters of the PCFs. The numerical solutions of the generalized nonlinear Schrödinger equation (GNLSE) for a secant hyperbolic input pulse at different pumping wavelengths at mid-infrared region are investigated by varying input pulse power and fiber lengths. About 3000 nm wide supercontinuum can be generated at pumping wavelength of 2400 nm and input pulse power of 3000W with the designs. Thus, the designs of the PCF can be employed for generating supercontinuum to be useful for medical imaging, bio-sensing, spectroscopy, wave division multiplexing (WDM) systems, and optical communication systems.

Arsenic-free low-loss sulfide glass fiber for mid-infrared supercontinuum generation

A low-loss and Arsenic-free sulfur-based chalcogenide fiber(Ge-Sb-S) was fabricated by a novel process of peeled-off extrusion. The fiber has an optical loss of <2 dB/m in a range from 5 to 6 μm with a minimum loss of 0.87 dB/m at 5.1 μm. A mid-infrared (MIR) supercontinuum (SC) spectrum covering 1.56–7.59 μm was generated from a 22-cm long fiber pumped with a femtosecond laser at 4 μm (−150 fs, 1 kHz). Simultaneously, we demonstrated that the optical fiber has a transmission efficiency of 53% at 4 μm, which is the key significance for applications such as IR night vision, bio-photonics, military defense and environmentally friendly industry.

Chalcogenide-glass polarization-maintaining photonic crystal fiber for mid-infrared supercontinuum generation

In this paper, we report the design and fabrication of a highly birefringent polarization-maintaining photonic crystal fiber made from chalcogenide glass, and its application to linearly-polarized supercontinuum generation in the mid-infrared region. The fiber was drawn using the casting method from As38Se62 glass which features a transmission window from 2 to 10 μm and a high nonlinear index of 1.13 × 10–17 m2 W−1. It has a zero-dispersion wavelength (ZDW) at 4.56 μm for the fast axis and 4.68 μm for the slow axis and, at average ZDW, a large birefringence of 6.5 × 10–4 and consequently strong polarization maintaining properties are expected. Using this fiber, we experimentally demonstrate supercontinuum generation spanning from 3.1 to 6.02 μm and 3.33–5.78 μm using femtosecond pumping at 4 μm and 4.53 μm, respectively. We further investigate the supercontinuum bandwidth versus the input pump polarization angle and we show very good agreement with numerical simulations of the two-polarization model based on two coupled generalized nonlinear Schrödinger equations.

Mid-infrared two-octave spanning supercontinuum generation in a Ge–Se–Te glass suspended core fiber

We report on both the fabrication and the application of a Ge–Se–Te glass-based suspended core fiber for mid-infrared supercontinuum generation. A two-octave spanning mid-infrared light source (from 3.25 to 13 µm) is experimentally demonstrated by pumping the chalcogenide fiber with sub-100 fs pulses at 8.6 µm. Numerical simulations of nonlinear pulse propagation as well as fiber properties are also provided and support experimental measurements.

Scaling power, bandwidth, and efficiency of mid-infrared supercontinuum source based on a GeO2-doped silica fiber

We demonstrate a supercontinuum source with a 20 dB bandwidth from ∼1 to ∼3 μm with output power exceeding 6 W based on a GeO2-doped silica fiber. This is the highest output power reported for a 3 μm supercontinuum source based on germania-doped silica fiber in an all-fiberized and compact size device. We further demonstrate a spectrum spanning from ∼1.7 to ∼3.4 μm (∼10 dB bandwidth from ∼1.8 to ∼3.2 μm) at a low power of tens of milliwatts with more than 50% power fraction above 2400 nm, which makes this source suitable for several applications where a broadband source at low power is required to avoid damage of the samples. Our investigations reveal the unexploited potential of germania-doped fiber for mid-infrared supercontinuum generation and surpass the current state-of-the-art results.

Chalcogenide Microstructured Optical Fibers for Mid-Infrared Supercontinuum Generation: Interest, Fabrication, and Applications

The mid-infrared spectral region is of great technical and scientific importance in a variety of research fields and applications. Among these studies, mid-infrared supercontinuum generation has attracted strong interest in the last decade, because of unique properties such as broad wavelength coverage and high coherence, among others. In this paper, the intrinsic optical properties of different types of glasses and fibers are presented. It turns out that microstructured chalcogenide fibers are ideal choices for the generation of mid-infrared supercontinua. The fabrication procedures of chalcogenide microstructured fibers are introduced, including purification methods of the glass, rod synthesis processes, and preform realization techniques. In addition, supercontinua generated in chalcogenide microstructured fibers employing diverse pump sources and configurations are enumerated. Finally, the potential of supercontinua for applications in mid-infrared imaging and spectroscopy is shown.

Dispersion-engineered microstructured optical fiber for mid-infrared supercontinuum generation.

Due to the large scientific and technical interest in the mid-infrared (MIR) spectral region, and the limitations of MIR light sources, we focus on the generation of a broad supercontinuum inside a short piece of As2Se3 microstructured optical fiber (MOF) with a square lattice. This is accomplished by filling the holes in the innermost ring of the proposed MOF with Ge33As12Se55 to produce ultraflat and near-zero dispersion. Simulations reveal that, by launching 100fs input pulses centered at λ0=6.2 μm with a peak power of 2kW into the MOF, an optical spectrum as wide as 9.5μm will be achieved. This spectrum is a suitable source for MIR applications such as spectroscopy, food quality control, and gas sensing.

Record power, ultra-broadband supercontinuum source based on highly GeO2 doped silica fiber.

We demonstrate highly germania doped fibers for mid-infrared supercontinuum generation. Experiments ensure a highest output power of 1.44 W for a broadest spectrum from 700 nm to 3200 nm and 6.4 W for 800 nm to 2700 nm from these fibers, while being pumped by a broadband Erbium-Ytterbium doped fiber based master oscillator power amplifier. The effect of repetition frequency of pump source and length of germania-doped fiber has also been investigated. Further, germania doped fiber has been pumped by conventional supercontinuum source based on silica photonic crystal fiber supercontinuum source. At low power, a considerable broadening of 200-300 nm was observed. Further broadening of spectrum was limited due to limited power of pump source. Our investigations reveal the unexploited potential of germania doped fiber for mid-infrared supercontinuum generation. These measurements ensure the potential of germania based photonic crystal fiber or a step-index fiber supercontinuum source for high power ultra-broad band emission being by pumped a 1060 nm or a 1550 nm laser source. To the best of our knowledge, this is the record power, ultra-broadband, and all-fiberized supercontinuum light source based on silica and germania fiber ever demonstrated to the date.

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.

Tapered chalcogenide–tellurite hybrid microstructured fiber for mid-infrared supercontinuum generation

Fibers exhibiting flattened and decreasing dispersion are important in nonlinear applications. Such fibers are difficult to design, particularly in soft glass. In this work, we develop a preliminary design of a highly nonlinear tapered hybrid microstructured optical fiber (TH-MOF) with chalcogenide glass core and tellurite glass microstructure cladding. We then numerically studied its dispersion, loss, and nonlinearity-related optical properties under fundamental mode systematically using the infinitesimal method. The designed TH-MOF exhibits low chromatic dispersion that is similar to a convex function with two zero-dispersion wavelengths and decreases with fiber length from 2 to 5 μm band. The potential use of the TH-MOF in nonlinear applications is demonstrated numerically by a supercontinuum spectrum of 20 dB bandwidth covering 1.96–4.76 μm generated in 2-cm-long TH-MOF using near 3.25-μm fs-laser pump.