• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.44-49
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• 2013

A transimpedance amplifier (TIA)-optical receiver (Rx) using two intersecting active feedback system with regulated-cascode (RGC) input stage has been designed and implemented for optical interconnects. The optical TIA-Rx chip is designed in a 0.13 ${\mu}m$ CMOS technology and works up to 10 Gbps data rate. The TIA-Rx chip core occupies an area of 0.051 $mm^2$ with power consumption of 16.9 mW at 1.3 V. The measured input-referred noise of optical TIA-Rx is 20 pA/${\surd}$Hz with a 3-dB bandwidth of 6.9 GHz. The proposed TIA-Rx achieved a high gain-bandwidth product per DC power figure of merit of 408 $GHz{\Omega}/mW$.

• Current Optics and Photonics
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• v.4 no.6
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• pp.558-565
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• 2020

A wavelength-independent optical sensor based on an asymmetric Mach-Zehnder interferometer (AMZI) is proposed. The optical sensor based on an AMZI is very sensitive to wavelength, and wavelength drift will lead to measurement error. The optical sensor is compensated to reduce its dependence on wavelength. The insensitivity of the optical sensor to wavelength mainly depends on the compensation structure, which is composed of an AMZI cascaded with another AMZI and can compensate the wavelength drift. The influence of wavelength drift on the optical sensor can be counteracted by carefully designing the size parameters of the compensation structure. When the wavelength changes from 1549.9 nm to 1550.1 nm, the error after compensation can be lower than 0.066%. Furthermore, the effect of fabrication tolerance on compensation results is analyzed. The proposed compensation method can also be used to compensate the drift of other parameters such as temperature, and can be applied to the compensation of other interference-based optical devices.

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.58-62
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• 2019

Diffractive Optical Elements(DOEs) diffracts incident light using the diffraction phenomenon of light to generate a desired diffraction image. In recent years, the use of diffraction optics, which can replace existing refractive optical elements with flat plates, has been increased by implementing various optical functions that could not be implemented in refractive optical devices and by becoming miniaturized and compacted optical elements. Direct laser lithography is typically used to effectively fabrication such a diffractive optical element in a large area with a low process cost. In this study, the process conditions for fabricating patterns of diffractive optical elements in various shapes were found using direct laser lithographic system, and optical performance evaluation was performed through fabrication.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.251-252
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• 2008

We fabricated silica glass optical fiber containing PbSe quantum-dots (QD) of average size 3.2 nm. The response time of the PbSe-QD doped optical fiber was measured to be around 200 ps. However, after exposure to 1064 nm laser emission for 15 minutes, the response time dramatically reduced to around 2.5 ps, which may be due to photo-darkening effect.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.9-10
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• 2006

We report the realization of the Yb/Tm co-doped silica glass optical fiber amplifier operating at 1470 nm upon 980 nm pumping. The energy transfer coefficient from Yb to Tm was estimated using the threshold condition of the optical amplifier.

• Transactions of the KSME C: Technology and Education
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• v.5 no.1
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• pp.53-61
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• 2017

In this review paper, the trend for optical technology is described as the development of mechanical industries in the $21^{st}$ century. Optical technology has been essential in various industries such as mechanical, electronic industries as the convergence technology. Based on the roadmap of optical science and technology, 12 working groups are categorized as the technical point of view and most of them are closely related to mechanical industries. Especially, solid-state lighting, optical metrology and industrial laser processing are important technologies in precision engineering and manufacturing. This paper introduces these optical technologies and their technological issues to look into the development trends and expectation.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.397-402
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• 2015

In this paper, we propose a method used to measure the polarization state of a field with multiple polarization singularities (PSs), such as an array of PSs and PSs in vector speckle. A checkerboard is used to construct characteristic points, which makes it possible to calibrate the mismatches between pictures obtained during the rotation of a quarter-wave plate and a polarizer. Using this method a field with an array of PSs is measured. The experimental result is compared with the numerical simulation. We also carry out some data analysis. The comparison and analysis emphasize the necessity and feasibility of this method to measure the PSs.

• ETRI Journal
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• v.28 no.1
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• pp.119-122
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• 2006

We present an intelligent optical switching structure based on our lambda-group model along with a working scheme that can provide a distinctive approach for dividing complicated traffic into specific tunnels for better optical performance and grooming efficiency. Both the results and figures from our experiments show that the particular channel partition not only helps in reducing ports significantly, but also improves the average signal-to-noise ratio of the wavelength channel and the blocking performance for dynamic connection requests.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2464-2466
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• 1998

A switch is a component with two or more ports that selectively transmits, redirects, or blocks optical power in a fiber transmission line. Our switch uses rotation mechanism using stepping motor, hence the common optical fiber can scan and allign to one of the arrayed N optical fibers to provide optical path by electronic precise control. The developed switch is consisted of switching module and its control module. The performance parameters of a switching loss and a repeatability are considered very important. We performed the study to reduce the switching loss and improve the repeatability of switch. The switch can be widely used as a test instrument of optical device and of optical cable in factory, also of optical cable monitoring systems.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.307-309
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• 2003

In the initial deployment stage of optical access networks, optical network systems and optical fiber cables have been provided mainly for commercial buildings or users in KT. According to the demand of residential users who expect to subscribe broadband multimedia services as high bit rate services, the optical access networks get closer to the residential users as FTTCab or FTTH So, it is very important to install optical access networks economically and effectively because that the total cost and usability of optical fiber cables depends on that. Especially, one of characteristics in access networks is the possibility of variation on services demands and technology evolution. Also access networks must be prepared for the final deployment, FTTH. Therefore, the designing and planning of optical access networks are coming to be very important activity for most of telecommunications service providers.