• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.4
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• pp.55-62
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• 2002

FRLGC(Fiber Ring laser Gain Clamped) EDFA Is demonstrated for an automatic gain control in hi-directional ADM(Add Drop Multiplexer) node configuration. Specifically, we investigate hi-directional characteristics of noise figure. Assuming a hi-directional small signal input, noise figures for forward or backward signal input are calculated using average inversion algorithm, according to the propagating directions and lasing wavelengths of a compensating signal. The operating condition of FRLGC-EDFA may be optimized with a backward lasing and short lasing wavelength in the aspect of hi-directional noise figure characteristics.

• Journal of the Optical Society of Korea
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• v.1 no.2
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• pp.110-115
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• 1997

We report effcient cascaded Raman generation and signal amplification at 1.3.mu.m achieved in a ring resonator constructed solely from fiber components, i.e. fusion WDM couplers. Low-loss single-mode fiber with moderate $GeO_2$ content (18 mole %) is used as an active medium and pumped by a Nd:YAG laser at 1.064.mu.m. In a resonant cascaded geometry, this generates the third Stokes line at 1.24.mu.m, which acts as a pump for signal wavelength around 1.3.mu.m. A DFB laser operating at 1.315.mu.m is used to provide an input signal. An output signal powers up to 20 dBm (100 mW) with a 28 dB Raman gain are attained, where the Nd:YAG pump power is 3.4 W. It is also shown experimentally that it is important to use optical filters to suppress feedback from the resonator, permitting high Raman gain and good signal quality.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.142-143
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• 2000

파장분할 다중화 방식(WDM)이 광통신 시스템의 통신 속도를 획기적으로 향상시키는 방법으로 자리잡음에 따라 다파장 발생에 관한 많은 연구가 이어지고 있다. 지금까지의 연구 결과들은 크게 두가지로 나눌 수 있는 데, 넓은 대역의 이득 매질에서 다양한 방식의 파장선택 특성들을 이용하여 여러 개의 파장을 원하는 간격으로 발생시키는 방법$^{(1).(2)}$ 과 하나의 외부레이저 신호입사에 의한 유도산란을 통하여 일정한 파장간격을 가진 연속차수의 스토크스 신호를 발생시키는 방법$^{(3).(4).(5)}$ 이 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.182-183
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• 2002

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.211-216
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• 2012

We report a resonance fiber Bragg sensor interrogation based on a Fourier domain mode-locking (FDML) laser. The FDML laser is constructed based on a conventional ring laser cavity configuration with fiber Fabry-Perot tunable filter (FFP-TF). There are two sensor parts which are composed with two FBGs inside the laser cavity. Each sensor part provides a separate laser cavity for the FDML laser. The resonance frequencies of the laser cavities are 46.687 kHz and 44.340 kHz, respectively. We applied a static and a dynamic strain on the FBG sensor system. The slope coefficients of the measured relative wavelength shift and relative time interval from the static strain are found to be $0.61pm/{\mu}{\epsilon}$ and $0.8ns/{\mu}{\epsilon}$, respectively.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.40-45
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• 2011

Design and fabrication of a TCRR (Triple-coupler Ring Resonator) filter which can provide a doubled FSR (Free Spectral Range) compared with a conventional DCRR (Double-coupler Ring Resonator) filter, are discussed. Through the use of a polymer material with a good thermo-optic property and with high contrast between core and cladding polymer, a compact TCRR filter composed of straight and curved buried waveguides of small radius is designed and fabricated. The transmission characteristics from the through and drop ports are measured using a tunable laser and a fiber array block, and the FSR is observed to be 4.4 nm, about twice that of DCRR filter, and almost the same as that obtained from the analysis using a transfer matrix method.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.15-20
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• 2002

We demonstrate a widely-tunable wavelength converter based on four-wave mixing in a semiconductor-fiber ring laser with no external pump light. Applying 10 GHz short pulses at -8 dBm as a probe signal, we achieve continuous wavelength tuning over the semiconductor optical amplifier gain-bandwidth reaching 30 nm down- and 17 m up-wavelength conversion. In addition to the wide tuning capability, the converter shows high-speed conversion and low saturation power capabilities.

• Korean Journal of Optics and Photonics
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• v.25 no.6
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• pp.340-345
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• 2014

We experimentally demonstrate the use of a gold-deposited side-polished fiber as a $2-{\mu}m$-band polarizing device to produce mode-locked pulses from a thulium/holmium-codoped fiber ring cavity. The mode-locking effect was induced by nonlinear transmission caused by the gold-deposited side-polished fiber, due to nonlinear polarization rotation of the oscillated beam within the fiberized cavity. It is also shown that ~558-fs pulses with a peak power of ~6.7 kW could readily be produced at a wavelength of 1935 nm through subsequent thulium/holmium-codoped fiber amplification, due to the higher-order soliton compression effect.

• Korean Journal of Optics and Photonics
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• v.28 no.1
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• pp.22-27
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• 2017

Time-encoded near-infrared spectroscopy (NIRS) system is proposed, based on a near-infrared (NIR) swept laser source, for comparison to the conventional NIRS method using a detector-type spectrometer. The cavity of the NIR swept laser source consists of a semiconductor optical amplifier (SOA) with a gain region around 800 nm, and several fiber-optic components. To change the output wavelength in time using an applied electric radio-frequency signal, an acousto-optic tunable filter (AOTF) is introduced in the fiber ring cavity configuration. To demonstrate the feasibility of an NIR swept laser source for NIRS imaging, the spectroscopic comparison of two kinds of absorbance-measuring systems a detector-type spectrometer using a white light source, and a source-type spectrometer using an NIR swept laser is successfully performed with an NIR-absorbing dye.

• Journal of IKEEE
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• v.5 no.2 s.9
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• pp.201-210
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• 2001

Wavelength and repetition-rate tunable optical pulse-trains for ultrafast optical time- and wavelength division multiplexing are generated from a semiconductor fiber ring laser by optical injection mode-locking. The pulse trains show the pulse with of ${\sim}10$ ps and the wavelength tuning of wider than 30 nm at various repetition-rates of 10 GHz, 20 GHz, 30 GHz and 40 GHz, respectively.