• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.564-568
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• 2014

We present a 25-Gb/s optical transmitter composed of a Si ring modulator and CMOS driver circuit. The Si ring modulator is realized with 220-nm Si-on-insulator process and the driver circuit with 65-nm CMOS process. The modulator and the driver are hybrid-integrated on the printed circuit board with bonding wires. The driver is designed so that the parasitic bonding wire inductance provides enhanced driver bandwidth. The transmitter successfully demonstrates 25-Gb/s operation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.141-145
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• 2011

We theoretically investigated dispersion tolerance of an optical duobinary transmitter employed a Mach-Zehnder modulator and an optical filter. Compared to the optical transmitter based on a Mach-Zehnder modulator and an optical delay interferometer by optimizing the applied voltage for improving the dispersion tolerance, the demonstrated duobinary transmitter provides improved receiver sensitivity and higher dispersion tolerance while maintaining narrow spectral bandwidth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.817-820
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• 2002

In this letter, we developed a 400Gb/s optical transmitter using an electroabsorption modulator and measured its characteristics. As a result, the extinction ratio, the output power and the wavelength are varied while DC bias voltage and temperature of an electroabsorption modulator are changed. Based upon these experimental results, a design of 400Gb/s optical transmitter can be optimized.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.3
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• pp.221-228
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• 2011

This paper describes 250-Mb/s fiber optic transmitter and receiver ICs for plastic optical fiber applications using a$ 0.18-{\mu}m$ CMOS technology. Simple signal and light detection schemes are introduced for power reduction in sleep mode. The transmitter converts non-return-to-zero digital data into 650-nm visible-red light signal and the receiver recovers the digital data from the incident light signal through up to 50-m plastic optical fiber. The transmitter and receiver ICs occupy only 0.62 $mm^2$ of area including electrostatic discharge protection diodes and bonding pads. The transmitter IC consumes 23 mA with 20 mA of LED driving currents, and the receiver IC consumes 16 mA with 4 mA of output driving currents at 250 Mb/s of data rate from a 3.3-V supply in active mode. In sleep mode, the transmitter and receiver ICs consume only 25 ${\mu}A$ and 40 ${\mu}A$, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.10-17
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• 1994

Two protocols inclouding the receiver collision avoidance function are proposed for high-speed optical fiber LANs with finite users. The basic idea to avoid receiver collision is the grouping of destination nodes by the number of channels and it is accomplished in the architecture with or without one separate control channel. While the protocol with a control channel requires a tunable optical transmitter, a fixed optical transmitter and two fixed optical receiver, the other protocol requires a tunable optical transmitter and one fixed optical receiver. The performance of two receiver collision avoidance protocols is computed and analyzed under various system parameters. The numerical results show that the receiver collision avoidance protocol has better performance for a small load than the protocol without receiver collision avoidance.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.179-186
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• 2000

Optical coupling coefficients and misalignment tolerance of 155 Mbps optical transmitter module of passive alignment technology, to be usable in ATM system, B-NT (Broadband Network Termination) system, and 10 G transmission system for information super-highway networks, were calculated, compaired with it's engineer samples, and discussed. These engineer samples of -4.5 dBm maximum output power were packaged in the method of butt coupling of flat-fiber and tested reliability evaluation. Hence the cheap packaging method of optical transmitter module was researched. rched.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.47-55
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• 1996

An optical transmitter, which is a key component of the optical transmission system, converts the electrical signal to optical signal and consists of a high-speed current-pulse driver for laser diode and low-speed feedback loops that stabilize optical power against aging, power supply voltage fluctuations, and ambient temperature changes. In this paper, the power-stabilizing part, which forms the bulk of the optical transmitter circuitry was designed in integrted circuits. Operational amplifiers and reference voltage generation circuits, which were identified as key building blocks for the power-stabilizing feedback loops, were designed and were subsequently verified through HSPICE simulations. The designed operational amplifier consists of a two-stage folded cascode amplifier and class AB output stage, whereas the reference voltage is obtained by bandgap reference circuits. Finally the power-stabilizing circuitry was laid out based on 3\mu$m CMOS design rules for fabrication.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.25-30
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• 2007

In this paper, we proposed a new burst-mode optical transmitter structure which is suitable for high data rate operation such as Gb/s operation. With this structure we made a 1.25Gb/s burst-mode optical transmitter including a digitally controlled APC circuit for EPON systems using commercial 0.8m BiCMOS technology. It well functioned at 1.25Gb/s and showed good eye patterns with 53.3ps jitter, 191ps rise time and 258ps fall time. To characterize the APC function we measured optical output power as increasing external voltage VREF. The optical power is linearlyproportional to VREF at the rate of 0.293mW/V.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.158-170
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• 2004

Wireless optical communication is expected for high-speed optical communication in the areas of saturated optical fiber communication and low population density. In this paper, we present an optical transmitter system for wireless optical communication with new design concepts different from the usual optical imaging system. The specifications are the following: the source is a laser diode(LD) of wavelength 830 nm in which the divergent angle from the tangential plane differs from that from the sagittal plane. Here, the requested transmission distances are very long range such as 500 m to 1500 m and beam diameter is 3 m at the receiver with symmetrical energy distribution. For the evaluation characteristics of this kind of non-imaging system, two optical quantities, the relative illumination distribution and energy transfer efficiency, are numerically calculated through lots of ray tracing.

• Korean Journal of Optics and Photonics
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• v.28 no.2
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• pp.75-82
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• 2017

We present a new type of receiver-transmitter optical system that can be adapted to the sensor head of a displacement-measuring interferometer. The interferometer is utilized to control positioning error and repetition accuracy of a wafer, down to the order of 1 nm, in a semiconductor manufacturing process. Currently, according to the tendency of scale-up of wafers, an interferometer is demanded to measure a wider range of displacement. To solve this technical problem, we suggest a new type of receiver-transmitter optical system consisting of a GRIN lens-Collimating lens-Afocal lens system, compared to conventional receiver-transmitter using a single collimating lens. By adapting this new technological optical structure, we can improve coupling efficiency up to about 100 times that of a single conventional collimating lens.