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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Optical Society of Korea
Journal Basic Information
Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 7, Issue 4 - Dec 2003
Volume 7, Issue 3 - Sep 2003
Volume 7, Issue 2 - Jun 2003
Volume 7, Issue 1 - Mar 2003
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Effect of Soaking Temperature on Erbium Doping of Optical Fiber Core in MVCD Solution Doping Process
Han, Won-Taek ; Kim, Yune-Hyoun ; Paek, Un-Chul ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 47~52
DOI : 10.3807/JOSK.2003.7.2.047
Effect of soaking temperature on erbium doping of the optical fiber core during solution doping procedure, especially in the modified chemical vapor deposition (MCVD) process, was investigated. The concentration of dopants such as
in the preforms and the optical fibers measured by the electron probe microanalysis (EPMA) and the optical spectrum analyzer (OSA) was found to increase with decreasing the soaking temperature. The increase in the concentration of the
is attributed to the precipitation of the erbium due to the decrease in the solubility as well as the increase of capillary force and viscosity of the doping solution by decreasing the temperature.
Mode Coupling within Inner Cladding Fibers
Lee, Byeong-Ha ; Eom, Tae-Jung ; Kim, Myoung-Jin ; Paek, Un-Chul ; Park, Tae-Sang ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 53~58
DOI : 10.3807/JOSK.2003.7.2.053
We report the formation of inner cladding modes in the optical fiber having an inner cladding structure. The inner cladding layer located between the core- and the cladding- layers of a conventional fiber might have, so called, inner cladding mode(s). The brief history of the inner cladding fiber and the spectral properties of the inner cladding mode are presented. By utilizing fiber gratings, the spectral properties of the inner cladding mode formed in Dispersion Compensating Fiber (DCF) are discussed. It was observed that one resonant peak of a long-period fiber grating was not sensitive to the variation on the cladding surface. With a fiber Bragg grating, a small group of unusual resonant Peaks was observed between the main Bragg Peak and the series of usual Peaks resulted from the mode coupling to counter-propagating cladding modes. Within the DCF by using fiber gratings, it is noted, at least one mode can be coupled to the inner cladding mode and a few outer cladding modes are severely affected by the inner cladding of the fiber.
Theoretical Study of the Effect of Pulse Chirping on Polarization Mode Dispersion and Polarization-Dependent Loss
Yoon, Il-Yong ; Lee, Yong-Wook ; Lee, Byoung-Ho ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 59~63
DOI : 10.3807/JOSK.2003.7.2.059
We accomplished numerical simulations for two-uniform-fiber concatenation with both polarization mode dispersion (PMD) and polarization-dependent loss (PDL) . The effective overall PMD is increased with the chirp parameter and the effective overall PDL is decreased with the chirp parameter. For PDL, chirping just makes the signal bandwidth wider, so makes the pulse be more depolarized than a chirp-free pulse. We showed that PDL increases the frequency dependence of the principal states of polarization, and the combination of this dependency and the bandwidth broadening by chirping can affect the effective PDL.
Double-Pass Two-Stage EDFA with Gain-Flattening Filters
Sohn, Ik-Bu ; Baek, Jang-Gi ; Song, Jae-Won ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 64~66
DOI : 10.3807/JOSK.2003.7.2.064
The optical gain and noise figure improved double-pass two-stage EDFA using a mirror, circulator, and gain-flattening filters is proposed. By double passing the pump light and removing the ASE propagating into the input part, the signal gain of 5 ㏈ and noise figure of 2.1 ㏈ are improved compared to the conventional single- and double-pass EDFA With gain-fattening filters in the second stage of EDFA, we obtain an improved flat gain with a gain flatness less than 1 ㏈ over 33-nm wavelength range at the 980-nm pump power of 86 ㎽.
Investigation of Amplifying Mechanism in an t-Band Erbium-Doped Fiber Amplifier Pumped by a 980 nm Pump
Lee, Dong-Han ; Lee, Han-Hyub ; Oh, Jung-Mi ; Kim, Byung-Jun ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 67~71
DOI : 10.3807/JOSK.2003.7.2.067
For a more detailed understanding of the mechanism of an L-band erbium-doped fiber amplifier, we investigated 980 nm absorption, signal amplification and forward and backward amplified spontaneous emission along the erbium-doped fiber. In addition, we compared performances of the erbium-doped fiber amplifier with and without a fiber Bragg grating.
Dependence of the Transmission Characteristics of Photonic Crystal Fiber on the Macrobending Radius and the Mechanically Induced Microbending
Lee, Byeong-Ha ; Moon, Dae-Seung ; Eom, Joo-Beom ; Kim, Jin-Chae ; Kim, Hok-Young ; Paek, Un-Chul ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 72~78
DOI : 10.3807/JOSK.2003.7.2.072
It is reported that the spectral loss of photonic crystal fiber (PCF) having a large hole-to-hole distance (~ 10
) is sensitive to micro- and macrobending when compared with the conventional single-mode fiber. In this paper, we will present the measurement result of the macro- and microbending characteristics of fabricated PCF with large hole-to-hole distance (> 10
) . For the macrobending experiment, the fiber was simply wound around a circular structure with variable diameter that could be reduced to a few centimeters. For the microbending case, regularly spaced silica rods were attached on a slide glass and pressed against the fiber by loading a stack of metal plates of known weight on the glass. The transmission loss spectrum shows a rather flat response to the to microbending, and this makes the PCF a good candidate for a wideband variable optical attenuator.
The Fabrication of a Photonic Crystal Fiber and Measurement of its Properties
Kim, Jin-Chae ; Kim, Ho-Kyung ; Paek, Un-Chul ; Lee, Byeong-Ha ; Eom, Joo-Beom ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 79~83
DOI : 10.3807/JOSK.2003.7.2.079
In this paper, we describe the fabrication process of a photonic crystal fiber and present the measured optical properties of the photonic crystal fiber. The fabrication of the photonic crystal fiber involves stacking, jacketing, collapsing, and drawing using a conventional drawing tower The photonic crystal fiber drawing needs higher tension to maintain the uniform air hole structure. Thus, the temperature of the photonic crystal fiber drawing is lowered by a few hundred degrees Celsius than for the case of conventional optical fiber drawing. The optical properties of the fabricated photonic crystal fiber such as mode profile, optical loss, transmission spectrum, bending loss, and polarization dependent loss are measured.
New Compensation Method for Temperature Sensitivity of Fiber Brags Grating Using Bi-metal
Chung, Young-Joo ; Song, Jong-Seob ; Han, Won-Taek ; Paek, Un-Chul ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 84~88
DOI : 10.3807/JOSK.2003.7.2.084
A new method for temperature compensation of fiber Bragg grating (FBG) using hi-metal is proposed and experimentally demonstrated. Bi-metal bends toward the metal of low temperature expansion coefficient as the temperature increases, and this property is utilized to cancel the thermo-optic effect of the fiber. The optimum thickness of the high coefficient metal was empirically found by the trial-and-error method. The temperature sensitivities were 8.1 pm/
and -0.018 pm/
for the uncompensated and compensated FBGs, respectively, which indicates a reduction to a mere 0.22 % of the original sensitivity. No appreciable change in the spectral shape was observed. The packaging technique described in this paper is simple and compact, and it can be used for FBGs in WDM and DWDM communication systems that have stringent requirements on the temperature stability of the components.
Control of Free Spectral Range of tong Period Fiber Grating by Cladding Mode Waveguide Dispersion
Jeong, H. ; Oh, K. ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 89~96
DOI : 10.3807/JOSK.2003.7.2.089
A new method to control the free spectral range of a long period fiber grating is proposed and theoretically analyzed. As the refractive index decreases radially outward in the silica cladding due to graded doping of fluorine, waveguide dispersion in the cladding modes was modified to result in the effective indices change and subsequently the phase matching conditions for coupling with the core mode in a long period fiber grating. Enlargement of the free spectral range in a long period fiber grating was theoretically confirmed.
Novel Raman Fiber Laser and Fiber-Optic Sensors Using Multi-Channel Fiber Gratings
Han, Young-Geun ; Kim, Sang-Hyuck ; Lee, Sang-Bae ; Kim, Chang-Seok ; Kang, Jin-U. ; Paek, Un-Chul ; Chung, Young-Joo ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 97~101
DOI : 10.3807/JOSK.2003.7.2.097
The transmission characteristics of multi-channel long period fiber gratings (LPFGs) in terms of the physical parameters like the separation distance, grating length and number of gratings will be discussed. Their transmission characteristics such as channel spacing, number of channels, loss peak depth, and channel bandwidth can be easily controlled by physical parameters. Based on the experimental results, their applications to optical multiwavelength Raman lasers and optical sensors will be investigated. A multiwavelength Raman fiber ring laser with 9 WDM channels with 100 ㎓ spacing and 19 channels with 50 ㎓ spacing using tunable multi-channel LPFGs will be experimentally demonstrated. The fiber-optic sensing applications with high resolution and sensitivity based on multi-channel LPFGs will be also presented.
A Fiber Optic Sensor for Measurements of Solute Concentration in Fluids
Kim, Chang-Bong ; Su, C.B. ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 102~105
DOI : 10.3807/JOSK.2003.7.2.102
A new and simple calibration technique that greatly enhances the measurement sensitivity of conventional fiber-optic reflectometry based on Fresnel reflection from the tip of a fiber is used for demonstrating the feasibility of measuring solute concentrations and index changes in fluids to very high precision. The amplitude of pulses originating from reflection from the fiber-fluid interface is compared in real-time with the amplitude of reference pulses from a fiber-air interface such that errors caused by pulse amplitude fluctuations and slightly varying detector responses are corrected. Using solutions of salt and water, it is demonstrated that the technique is capable of measuring index changes of about
corresponding to a salt concentrations of 0.01 %.
Temperature Compensation of a Strain Sensing Signal from a Fiber Optic Brillouin Optical Time Domain Analysis Sensor
Kwon, Il-Bum ; Kim, Chi-Yeop ; Cho, Seok-Beom ; Lee, Jung-Ju ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 106~112
DOI : 10.3807/JOSK.2003.7.2.106
In order to do continuous health monitoring of large structures, it is necessary that the distributed sensing of strain and temperature of the structures be measured. So, we present the temperature compensation of a signal from a fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor. A fiber optic BOTDA sensor has good performance of strain measurement. However, the signal of a fiber optic BOTDA sensor is influenced by strain and temperature. Therefore, we applied an optical fiber on the beam as follows: one part of the fiber, which is sensitive to the strain and the temperature, is bonded on the surface of the beam and another part of the fiber, which is only sensitive to the temperature, is located nearby the strain sensing fiber. Therefore, the strains can be determined from the strain sensing fiber while compensating for the temperature from the temperature sensing fiber. These measured strains were compared with the strains from electrical strain gages. After temperature compensation, it was concluded that the strains from the fiber optic BOTDA sensor had good coincidence with those values of the conventional electrical strain gages.
Two-Photon Interference Experiment in a Mach-Zehnder Interferometer
Kim, Tae-Soo ; Kim, Heon-Oh ; Ko, Jeong-Hoon ; Park, Goo-Dong ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 113~118
DOI : 10.3807/JOSK.2003.7.2.113
A two-photon interference experiment is presented in which an entangled pair of photons generated from a parametric down-conversion was incident on two input ports of a Mach-Zehnder interferometer. The experiment was carried out using two photon coincidence detection with two detectors at the two output ports of the interferometer. The measured coincidence counts exhibit an interference effect with visibility of 0.75 at simultaneous inputs and 0.38 at inputs with different arrival times according to the degree of photon number entanglement.
Observation of Parametric Resonance in a Magneto-Optical Trap
Jhe, Won-Ho ; Noh, Heung-Ryoul ; Kim, Ki-Hwan ; Ha, Hyun-Ji ;
Journal of the Optical Society of Korea, volume 7, issue 2, 2003, Pages 119~125
DOI : 10.3807/JOSK.2003.7.2.119
We demonstrate parametric resonance in a magneto-optical trap. When we modulate the intensity of the cooling laser at about twice the resonant frequency of the trap, the atoms in the trap are divided into two parts and oscillate with 180 degree phase difference with the finite length due to nonlinearity of the trap potential. These are the effects of general nonlinear dynamics, called the Hopf bifurcation, or limit cycle motion. The amplitude and the phase of the oscillations are measured and compared with the theoretical calculations based on simple Doppler cooling theory. The experimental results are in excellent agreement with the simulation results based on the simple Doppler cooling theory.