[Show abstract][Hide abstract] ABSTRACT: We present a low coherent hybrid detection technique for the differential model delay (DMD) measurement of a conventional optical multimode fiber with a modified Mach-Zehnder interferometer. A low coherent hybrid detection technique enhances mode coupling between guided modes and the reference mode to easily resolve the modal distribution. An optical spectrum analyzer and a broadband source were used to obtain time-resolved optical beat signals. The measured interference signal was Fourier transformed to obtain time-delay information. A scanning offset launching method was used to excite every available mode in a multimode fiber (MMF). Measurements of a conventional 8-m-long MMF demonstrated the validity of our proposed method. The experimental results of our proposed method agree well with results obtained using a conventional time domain measurement method. Our proposed method can be used to measure the DMD in a short length of optical MMF with a temporal resolution better than 0.72 ps when using an 8-m-long single-mode fiber as a reference.
[Show abstract][Hide abstract] ABSTRACT: We present a novel spectrum-slicing method for measuring the chromatic dispersion of an optical fiber in Fourier-domain low-coherence interferometry. Broadband spectral interference data obtained from a low-coherence interferometer is sliced with Gaussian window functions. Each sliced spectral datum is used to calculate a relative group delay with Fourier transformation at the peak wavelength of a narrow window function. We have demonstrated that our proposed method is very powerful and simple for measuring chromatic dispersion and second-order dispersion in optical fibers and optical devices. Comparison of the proposed method with a conventional measurement method agrees within 0.5%.
[Show abstract][Hide abstract] ABSTRACT: We present a novel differential mode delay (DMD) measurement method for a multimode optical fiber (MMF) based on Fourier-domain low-coherence interferometry (fLCI) for the first time. An optical spectrum analyzer and a mode scrambler were used to obtain intermodal interference signal in spectral-domain after light pass an MMF. The MMF was used as a common path interferometer by itself without using any reference arm in an interferometer. Our proposed method can measure a short or long optical multimode fiber simply, accurately, and rapidly.
[Show abstract][Hide abstract] ABSTRACT: A novel differential mode delay (DMD) measurement for a multimode optical fiber using the Fourier-domain low-coherence interferometry (fLCI) for the first time has been proposed. Our experimental results have a good agreement with those results obtained using a conventional method
[Show abstract][Hide abstract] ABSTRACT: A new phase-matching condition for a four-wave-mixing (FWM) experiment in an optical fiber is proposed to simultaneously measure the linear and nonlinear optical properties of an optical fiber such as dispersion-zero wavelength, dispersion slop, and nonlinear refractive index. Several different dispersion shifted fibers (DSFs) and nonzero dispersion shifted fibers (NZDSFs) were tested to demonstrate the validity of our proposed method. We have also shown that experimental results are in good agreement with those obtained using a conventional measurement method. We believe that technique is a very powerful and efficient tool for zero-dispersion and dispersion slop mapping for already installed optical fibers.
[Show abstract][Hide abstract] ABSTRACT: We propose a novel transmission scheme to extend the single-mode operation range of a conventional single-mode fiber (C-SMF) to wavelengths shorter than the cutoff wavelength. It involves the use of a tapered-fiber mode filter (MF) in order to remove the high-order-mode power from the C-SMF and hence, makes the fiber work as a virtually single-mode transmission link. High-order mode suppression of above 10 dB has been achieved at wavelengths of 850 and 980 nm with a fabricated tapered-fiber MF. We have also demonstrated the feasibility of the technique by evaluating the transmission quality with the MF at 850 nm through a 5-km C-SMF having a cutoff wavelength of 1.2 μm.
[Show abstract][Hide abstract] ABSTRACT: A novel differential mode delay (DMD) measurement technique for a multimode optical fiber based on optical frequency domain reflectometry (OFDR) has been proposed. We have obtained a high-resolution DMD value of 0.054 ps/m for a commercial multimode optical fiber with length of 50 m by using a modified OFDR in a Mach-Zehnder interferometer structure with a tunable external cavity laser and a Mach-Zehnder interferometer instead of Michelson interferometer. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method. DMD resolution with our proposed OFDR technique is more than an order of magnitude better than a result obtainable with a conventional time-domain method.
[Show abstract][Hide abstract] ABSTRACT: A novel mode analysis method and differential mode delay (DMD) measurement technique for a multimode optical fiber based on optical frequency domain reflectometry has been proposed for the first time. We have used a conventional OFDR with a tunable external cavity laser and a Michelson interferometer. A few-mode optical multimode fiber was prepared to test our proposed measurement technique. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method.
[Show abstract][Hide abstract] ABSTRACT: We have experimented a plethysmograph sensor as a "MackJin" signal detector. Especially, "Kwan" signal was compared using the plethysmograph sensor. For the comparison, systolic peaks corresponding to the beats from each sensor were used. The experimental result proved that the photoplethysmogram is measured precisely with typical SPO2 sensor. The matters to be studied in the future are the improvement of natural property of detection probe and measuring method, the implementation of system which measures pulse wave of several positions at the same time, the implementation of system which controls gain and offset of the machine automatically, the collect of experimental data, and the proof of diagnosis result by oriental doctors.
[Show abstract][Hide abstract] ABSTRACT: We report detailed axial stress distribution along the splice between dissimilar optical fibers. Variation in magnitude, sign as well as discontinuity in the stress distribution were experimentally analyzed for splicing DCF, DSF and EDF with SMF.
[Show abstract][Hide abstract] ABSTRACT: This study reports a two-step laterally tapered 1.55 μm SSC DFB LD (spot-size converted distributed feedback laser diode) fabricated by using a non-selective grating process. While the use of the non-selective grating process makes the device fabrication process simpler, it produces an unwanted wavelength peak when used for a SSC DFB LD. The two-step lateral tapered SSC section is effective in eliminating the unwanted wavelength peak observed in the traditional single-step lateral tapered SSC DFB LD.
[Show abstract][Hide abstract] ABSTRACT: We report experimental results on the development of residual stress due to OH impurity in optical fibers. The effect of OH impurity on residual stress is demonstrated by direct residual stress measurement. The residual stress at the outer-cladding/jacketing-tube boundary of the fiber drawn at 3.48 N was found to be -61 MPa . The residual compressive stress is attributed to the viscosity decrease induced by a significant OH impurity at the boundary, as measured by a Fourier transform infrared microscope.
[Show abstract][Hide abstract] ABSTRACT: We have fabricated the tapered HF by using a fusion splicer and a fiber cleaver. We have experimentally observed the near-field mode profile of the HF and tapered HF. The mode field profile of the HF shows a good confinement of its field within the core diameter of the tapered HF. The mode pattern of the HF and tapered HF are all single mode. These properties can be potentially useful for improving the efficient coupling of light from an optical fiber into a planar waveguide.
[Show abstract][Hide abstract] ABSTRACT: In conclusion, we showed the behavior of bound solitons in a passively harmonic mode-locked figure-eight fiber laser with a DI-NOLM (nonlinear optical loop mirror). Autocorrelation trace and optical spectrum of bound solitons was presented. We have explained the spacing of quantized multi-pulses by using the gain depletion and recovery in the Ginzburg-Landow equation.
[Show abstract][Hide abstract] ABSTRACT: The compressive residual stress was found to develop at the outer-cladding/jacketing boundary of the optical fibers during the fiber drawing process. The residual stress of the fiber drawn at 3.48 N was found to be -61 MPa and it was due to the viscosity decrease induced by a significant OH impurity of ∼582 ppm.
[Show abstract][Hide abstract] ABSTRACT: The bulk photopolymerization of methyl methacrylate (MMA) with para-substituted phenylsilanes such as F- C6H4SiH3 (1), H3C-C6H4SiH3 (2), and H3CO-C6H4SiH3 (3) was performed to produce poly(MMA)s containing the respective silyl moiety as an end group. For all the hydrosilanes, the polymerization yields and the polymer molecular weights decreased, whereas the TGA residue yields and the relative intensities of Si-H IR stretching bands increased as the relative silane concentration over MMA increased. The polymerization yields and polymer molecular weights of MMA with 1-3 increased in the order of 3 < 1 < 2. These hydrosilanes influence significantly upon the photopolymerization of MMA as both chain-initiation and chain-transfer agents.
No preview · Article · Dec 2001 · Bulletin- Korean Chemical Society
[Show abstract][Hide abstract] ABSTRACT: We observed residual stress relaxation by CO(2) laser irradiation in the cores of optical fibers by direct stress measurement. It was demonstrated that the mechanical stress was fully relaxed by CO(2) laser irradiation and that the remaining stress in the core was thermal stress that was due to a mismatch of the thermal expansion coefficients of the fiber core and cladding. The net core stresses after relaxation were 17, 68, and 203 MPa in Ge-B-codoped fibers drawn at 0.53, 1.38, and 3.48 N, respectively. Changes in the refractive indices of the cores as a result of residual stress relaxation were also estimated.