• Korean Journal of Optics and Photonics
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• v.35 no.2
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• pp.61-70
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• 2024

We demonstrate a laser power meter calibration system based on 12-diode laser sources coupled to single-mode fibres in a wavelength range from 400 to 1,600 nm. In our system, three laser power controllers ensure that the output power uncertainty of all laser sources is less than 0.1% (k=2). In addition, all laser beams are adjusted to have similar beam sizes of approximately 2 mm (1/e²-width) at the measurement position to minimise unmeasured laser power on a detector. As a reference detector, we use an integrating sphere combined with silicon and indium gallium arsenide photodiodes to minimise the non-uniformity and non-linearity of responsivity. The minimum uncertainty of the calibration system is estimated to be 1.1% (k=2) for most laser wavelengths.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.214-220
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• 1997

A thin film optical waveguide sensor has been developed to measure and analyze quantitatively some inherent optical properties of biochemical substances. In this paper, two different kinds of thickness of thin film waveguide were prepared by RF sputtering of Corning-7059 glass(n = 1.588 at ${\lambda}=\;514nm$, Ar laser) on Pyrex glass substrates. We made a sensing membrane coated on the thin film waveguide with the poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohol) (91 : 3 : 6) copolymer membrane based on $H^{+}$-selective chromoionophore and $K^{+}$-selective neutral ionophore and then proposed the thin film opptical waveguide ion sensor which can select a potassium ion. This sensor based ell the absorbance change by utilizing chromoionophore and neutral ionophore, which changes their absorption spectrum in the UV-vis region upon complexation of the corresponding ionic species, have been reported. The sensitivity dependence of the proposed sensor on interaction length, waveguide thickness, and content of a chromoionophore was investigated. This sensor has the measurement range of $10^{-6}M{\sim}1M$ for $K^{+}$ concentration and 90% response time of duration within 1 min. Also, our thin film optical waveguide sensor using the evanescent field was investigated as compared with conventional transmission sensor or optode sensor by the optical fiber. The sensitivity of thin-film waveguide $K^{+}$ sensor is higher than that of the conventional transmission sensor. The proposed sensor is expected to be useful to biochemical, medical, environmental inspection and so on.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1134-1141
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• 1999

In this paper, we implement an optical code division multiple access(OCDMA) system and analyze the performance of the implemented system. In the implemented system, a transmitter encodes input data into optical pulses by using laser diode, and spreads the encoded pulses in an encoder which consists of 4 stage delay lines. The decoder which is the same structure as that of encoder delays and combines the spreaded pulses, and thus recovers the original data. At first, we discuss the auto- and cross-correlations of OCDMA signals under both environments of single user and multi-users, and then verify the simulation results with experimental results. We also evaluate the effect of a number of stages of delay line and code length on the system performance through computer simulations. As experimental results we can see that if the decoder have the same configuration as that of encoder, the peak auto-correlation characteristics can be achieved, and thus we can recover the original data from received data. As simulation results we can see that although bit error rate decreases as code length decreases or the number of stage of delay line increases, it is difficult to implement the system because the pulse width becomes narrow. From the results, we can apply CDMA technologies to optical communication networks.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.1-7
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• 1996

Optical intensity-type pressure sensor was fabricated by coupling optical fiber with a micromachined thin dielectric diaphragm, which consists of a 300 nm thick $SiO_{2}$ layer sandwiched between 150 nm thick top and bottom $Si_{3}N_{4}$ layers. At the wavelength of the sensor light source near $1.3\;{\mu}m$, the optical transmittance of the diaphragm was about 50 %, but it was decreased to a few percents by depositing $1,000\;{\AA}$ thick gold(Au) layer on the diaphragm, which is sufficient enough to be used as a light reflection layer of the sensor. From the optical output power-pressure characteristics of the sensors, it was found that the output power linearly decreased with increasing applied pressure from 0 to 77 torr regardless of the diaphragm size. The respective sensitivities were 0.52, 0.65, and 0.77 nW/torr for the diaphragm sizes of $3{\times}3$, $4{\times}4$, and $5{\times}5\;mm^{2}$, indicating that the sensitivity increases as diaphragm size decreases.

• Korean Journal of Optics and Photonics
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• v.24 no.4
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• pp.196-200
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• 2013

Heretofore, it was enough that most of optical transceiver modules for automotive networks have the performance of data rate from 10 Mbps to 150 Mbps. As the required data rate in automotive infotainment systems has recently been increasing, the development of a new optical transceiver having high speed data rate over 1Gbps is now required. Therefore, we suggested a next-generation bi-directional optical transceiver module using vertical cavity surface emitting laser technology and plastic clad fiber technology, for the next-generation automotive optical network, MOST1000. We fabricated the high-speed and compact optical transceiver having 1 Gbps data rate and -22 dBm sensitivity satisfying bit error rate $10^{-12}$.