We have theoretically proposed and experimentally demonstrated a new kind of ultranarrow identical-dual-bandpass sampled fiber Bragg gratings (SFBGs) with a pi phase shift technique. The spacing of two bandpasses of the proposed grating can be flexibly adjusted by changing the sampled period, and any desired spacing can be achieved in principle. An experimental example shows that the transmission peaks of two narrow transmission-band are near 1549.
View Article and Find Full Text PDFWe report a simple fiber sensor for measurement of high temperature with high sensitivity. The sensing head is a multimode-single mode-multimode (MM-SM-MM) fiber configuration formed by splicing a section of uncoated single mode fiber (SMF) with two short sections of multimode fibers (MMF) whose core is composed of pure silica. Because of the mode-field mismatch at the splicing points of the SMF with 2 sections of MMFs, as well as index matching between the core of the MMF and the cladding of the SMF, optical power from the lead-in fiber can be partly coupled to the cladding modes of the SMF through the MMF.
View Article and Find Full Text PDFA tunable comb filter based on a fiber loop mirror setup, which incorporates a piece of pumped erbium-ytterbium co-doped polarization maintaining fiber, is newly presented. It is accomplished by controlling the pump power or adjusting a polarization controller in the loop mirror, which results from the fact that the effective birefringence of the erbium-ytterbium co-doped polarization maintaining fiber depends on the pump power and polarization state of the traversing signal. By using the proposed comb filter, a continuously tunable multiwavelength fiber ring laser in the L-band is successfully demonstrated.
View Article and Find Full Text PDFFiber couplers made with photonic crystal fibers (PCF) are reported. Two types of PCF were fabricated by means of stacking a group of silica tubes around a silica rod and drawing them. The fiber couplers were made by use of the fused biconical tapered method.
View Article and Find Full Text PDFWe propose and experimentally demonstrate a tunable multi-wavelength SOA fiber laser based on a Sagnac loop mirror using elliptical core side-hole fiber. We fabricated different types of elliptical core side-hole fiber with elliptical or circular cladding shape. The measured modal birefringence of the fabricated fiber was 1.
View Article and Find Full Text PDFThe temperature sensitivity of modal birefringence (dB/dT) of different types of polarization-maintaining fibers with side holes was measured using a Sagnac loop interferometer. The thermal expansion coefficient can be varied by controlling the amount of germanium doped in the core region. Using this method, dB/dT could be made higher (~10(-7)/ degrees C) than that of standard PMFs (~10(-8)/ degrees C) or comparable to that of standard PMFs (~10(-9)/ degrees C).
View Article and Find Full Text PDFWe firstly report on the fabrication of Cu(2+)-doped germano-silicate glass fiber for nonlinear optical devices application by using modified chemical vapor deposition and solution doping processes. Broadband absorption near 700nm due to the 3d-shell electron transitions of Cu(2+) ions from the ground state to the excited states was observed. The resonant nonlinearity of the Cu(2+)-doped fiber was estimated to be 5.
View Article and Find Full Text PDFWe propose and experimentally demonstrate a simple multiwavelength Raman fiber laser based on few-mode fiber Bragg gratings without additional multichannel filters. The multiwavelength Raman laser output has a high extinction ratio of more than 45 dB. The multiwavelength output is so stable that the peak power fluctuation is less than 0.
View Article and Find Full Text PDFA novel and simple multi-wavelength linear-cavity tunable fiber laser source using a chirped fiber Bragg grating (CFBG) and a few-mode fiber Bragg grating (FMFG) is demonstrated using erbium-doped fiber (EDF) as the gain medium. In our linear-cavity configuration, the FMFG acts as full-reflecting mirror and wavelength selector while the CFBG with the 3-dB bandwidth of over 30 nm acts as a broadband partially reflecting mirror. The number of lasing wavelengths can be controlled by changing the state of polarization inside the cavity using a polarization controller.
View Article and Find Full Text PDFWe propose a simple erbium-doped fiber laser configuration for obtaining multi-wavelength oscillation at room temperature, in which a few-mode fiber Bragg grating was used as the wavelength-selective component. An amplitude variation of 1.6 dB over 120 second period was obtained for three-wavelength oscillation at room temperature, which demonstrates stability of the output power.
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