Large-core Photonic Crystal Fiber Research Articles

Supercontinuum generation in an all-normal dispersion large core photonic crystal fiber infiltrated with carbon tetrachloride

All-normal dispersion supercontinuum generation (SG) in a large hollow core photonic crystal fiber (PCF) infiltrated with carbon tetrachloride is studied experimentally. The PCF is optimized to have a flat normal dispersion in a broadband range (0.8–1.7 µm) varying from -150 to 0 ps/nm/km. The effective mode area at pump wavelength (λ=1030 nm) is as large as 42.2 µm2 and readily meets the requirements for an all-fiber supercontinuum system. Infiltration of the core with carbon tetrachloride ensures a high nonlinear coefficient of the fiber equal to 22 1/W/km. Using an off-the-shelf 1030 nm fiber laser with 400 fs and 25 nJ input pulses, we generated an all-normal supercontinuum in the 850–1250 nm wavelength range.

Raman-shifted wavelength-selectable pulsed fiber laser with high repetition rate and high pulse energy in the visible.

A high-pulse-energy, diffraction-limited, wavelength-selectable, visible source, based on Raman frequency shifting of a frequency-doubled Yb-doped fiber laser, has been studied. The relative length-scaling laws of Raman gain and self-phase modulation push the design towards short fiber lengths with large core size. It is experimentally demonstrated that the Raman clean-up effect in a graded-index multi-mode fiber is not sufficient to obtain diffraction-limited beam quality in the short fiber length. Thus, a large-core photonic crystal fiber is used to maintain diffraction-limited performance and output pulse energies of ~1 μJ, at a 1-MHz repetition rate and 1.3-ns pulse-width are successfully achieved. This step-tunable visible source should find applications in photoacoustic microscopy.

High numerical aperture large-core photonic crystal fiber for a broadband infrared transmission

In this paper we present a large mode area photonic crystal fiber made of the heavy metal oxide glass CS-740, dedicated for a broadband light guidance in the visible, near- and mid-infrared regions of wavelengths from 0.4 to 4.7μm. The fiber is effectively multi-mode in the considered wavelength range. It is composed of a ring of air-holes surrounding the core, with a high linear filling factor of 0.97. The fiber was made using a standard stack-and-draw technique. Each hole has a size of approx. 2.5×3.0μm and diameter of core is 80μm. Fiber attenuation is below 3dB/m in the 0.9–1.7μm wavelength range, while at 4.4μm (mid-IR) it is approx. 5dB/cm. Bending loss at the 1.55μm wavelength is 0.45dB per loop of 8mm radius. Fiber numerical aperture is 0.53 at 1.55μm. The effective mode area of the fundamental mode is approx. 2400μm2 in the wavelength range of 0.8–1.7μm. We present a proof-of-concept demonstration that our large core photonic crystal fiber is able to efficiently collect light directly from a mid-IR quantum cascade laser without use of additional optics and can be used for pigtailing mid-IR sources and detectors.

Visible supercontinuum generation in large-core photonic crystal fiber with high air-filling fraction

We demonstrate new experimental results for visible supercontinuum generation in large-core photonic crystal fiber with high air-filling fraction. Supercontinuum is generated by picosecond pulses from a passively mode-locked Yb:KGW laser. A smooth supercontinuum generation near 800 nm is achieved using 4.5 m long large-core photonic crystal fiber even with 6 mW average coupled power. These results are of interest in high power white light sources and have potential applications in precise frequency metrology and spectroscopy. The data obtained could be used also in theoretical studies of nonlinear interaction in large-core photonics crystal fibers with high air-filling fraction.

Characterization of a large core photonic crystal fiber made of lead–bismuth–gallium oxide glass for broadband infrared transmission

We report on characterization of a large solid core, photonic crystal fiber dedicated to broadband transmission range from visible to mid-infrared. We have fabricated a multi-mode photonic crystal fiber, made of a heavy metal-oxide glass based on the $$\hbox {PbO}{-}\hbox {Bi}_{2}\hbox {O}_{3}{-}\hbox {Ga}_{2}\hbox {O}_{3}$$ system, modified with $$\hbox {SiO}_{2}$$ and CdO, synthesized in-house, which shows good transmission up to $$4.5\,\upmu \hbox {m}$$ , as well as good rheological properties that permit multiple thermal processing steps without crystallization. The core of the fiber is created by replacement of central 60 tubes with solid rods. The photonic cladding is composed of 8 rings of air holes with a filling factor of 0.42. Simulation results shows that the fiber can be used for broadband transmission in the range of 430–3,000 nm. Calculated effective mode area of the fiber is $$295\,\upmu \hbox {m}^{2}$$ . We have measured attenuation of the fiber in the range 800–1,700 nm and its sensitivity to bending losses. Attenuation ranges from 1 to 4 dB/m in the considered range and bending losses are below 0.7 dB.

High power ytterbium-doped rod-type three-level photonic crystal fiber laser

In this paper, we investigate power scalability of ytterbium-doped ultra large core photonic crystal fiber laser operating on the zero-line transition. We first report on an 80 microm core diameter ytterbium-doped rod-type photonic crystal fiber laser emitting up to 94 W in continuous wave regime when operating at 977 nm, which is to our knowledge the highest output power ever achieved from a single-mode solid-state laser operating at this wavelength. Key parameters of ytterbium-doped three-level laser, such as transparency pump intensity, pump absorption saturation, and gain competition between three and four-level laser operation are then discussed in the particular context of high power fiber laser operating at 977 nm.