• Current Optics and Photonics
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• v.2 no.1
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• pp.27-33
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• 2018

We report the physical implementation of a tunable photonic microwave delay line filter based on injection locking of a single Fabry-Perot laser diode (FP-LD) to a reflective semiconductor optical amplifier (RSOA). The laser generates equally spaced multiple wavelengths and a single tapped-delay line can be obtained with a dispersive single mode fiber. The filter frequency response depends on the wavelength spacing and can be tuned by the temperature of the FP-LD varying lasing wavelength. For amplitude control of the wavelengths, we use gain saturation of the RSOA and the offset between the peak wavelengths of the FP-LD and the RSOA to decrease the amplitude difference in the wavelengths. From the temperature change of total $15^{\circ}C$, the filter, consisting of four flat wavelengths and two wavelengths with slightly lower amplitudes on both sides, has shown tunability of about 390 MHz.

• Journal of the Optical Society of Korea
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• v.2 no.2
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• pp.74-79
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• 1998

The use of a fiber Fabry-Perot interferometer (FFPI) as an optical current transducer is demonstrated. A conventional inductive pickup coil converts the time-varying current I(t) being measured to a voltage waveform V(t) applied across a piezeolectric strip to which the FFPI is bonded. The strip experiences a longitudinal expansion and contraction, resulting in an optical phase shift ${\phi}(t)$ in the fiber proportional to V(t). This phase shift is measured using a frequency-modulated semiconductor light source, photodiodes to monitor the reflected light from the FFPI and the laser power, and a digital signal processor. Calibration routines compute V(t) and I(t) from the measured phase shift at a l KHz rate. Response to 60 Hz ac over the design range 0-1300A rms is characterized Transient response of the FFPI transducer is also measured.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.359-364
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• 1995

A wavelength measurement system has been made using a monochromator and computer interfacing. The spectra of several light emitting diodes and the wavelength characteristics of Fabry-Perot LD and DFB LD have been measured with this system. The results show that this system can be practicalIy used in analyzing the lasing mode and the wavelength characteristics of the semiconductor lasers. asers.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.202-203
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• 2005

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.204-205
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• 2003

We demonstrate a novel OFDR system with compactness and short measurement time based on the use of a wavelength-swept mode-locked fiber laser. The optical source uses an intra-cavity tunable Fabry-Perot filter as a tuning element. The fiber laser sweeps 20 nm in less than 10 ms. Spatial resolution of 100 fm and total measurement range of several centimeters are demonstrate

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.411-417
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• 2000

The waveguide structure effects of a spot-size converter (SSe) of a $1.3\mu{m}$ FP(Fabry-Perot)-LD(Laser Diode) were investigated. Its coupling efficiency and alignment tolerance with a single-mode fiber (SMF) were carefully examined by using a 3dimensional BPM (Beam Propagation Method). It was shown that the fOlmation of enough length of straightened waveguide around the end of the sse region can substantially improve the optical coupling efficiency for a vertically tapered sse. In contrast, a down-taper structure for a laterally tapered sse has superior characteristics to an up-tapered one. We suggested good sse structures which can provide a high coupling efficiency as well as a large alignment tolerance with an .SMF. .SMF.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.8
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• pp.572-579
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• 2003

By comparing the measured optical reflection spectra with calculated one by the transfer-matrix method (TMM) in epitaxial wafers for vertical-cavity surface-emitting lasers (VCSELs), we have estimated the systematic thickness errors in a simple and nondestructive way. The experimentally confirmed technique is based on the finding that the shape of the reflection spectra depends mainly on a newly defined single parameter, the effective error in the n-mirror layers, and the thickness error in the active cavity simply shifts the Fabry-Perot resonance wavelength. Also shown is that the proposed method is reliable when the relative standard deviation of the random thickness errors is less than 0.005. Because reflection spectra are routinely measured, we can easily estimate the thickness errors nondestructively with high spatial resolution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.8-12
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• 2003

Characteristics of optical transceiver module in radio frequency(RF) band were investigated with TO-can packaged Fabry-Perot laser diode(FP-LD). R-L-C parameters for equivalent circuit model of the LD were extracted with an impedance analyzer. With this model, impedance matching to the packaged LD could be performed by eliminating inductive components of the leads in the package by using lumped chip capacitors that have opposite reactance, while it shows resonance dip in low frequency band. The resonance dip could be removed using lumped elements for impedance matching by shifting the resonance frequency to the region out of interest.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.102-103
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• 2005

Using THz time-domain spectroscopy, we study plasmonic band gaps in periodic metal arrays of slits. Femtosecnd machining system guarantees good quality sub millimeter structures for THz spectroscopy. Fabry-Perot effect enhances the transmission when the two resonances cross but does not alter the surface plasmon peak positions.