• Journal of the Optical Society of Korea
• /
• v.16 no.4
• /
• pp.401-408
• /
• 2012

The amplitude error of phase modulator used in closed-loop fiber optic gyroscope has occurred by the temperature dependency of the electro-optic coefficient, and also can be due to the square-wave dither signal which is generally applied for eliminating the deadzone. This error can cause bias drift and scale factor error. This paper analyzes the temperature dependency of the modulation amplitude and the relationship with the scale factor of the gyroscope, and deals with an amplitude control method. The error calculation logic considering the dither signal is implemented on the signal processing module. The result of experiments from a prototype gyroscope shows the effect of the modulation amplitude control and a considerable improvement on performances.

• Korean Journal of Optics and Photonics
• /
• v.17 no.5
• /
• pp.469-474
• /
• 2006

A $1{\times}16$ thermo-optic switch with small excess loss using multimode interference(MMI) couplers is designed, fabricated, and measured. This paper introduces the proposed $1{\times}16$ thermo-optic switch, and discusses the measurement results. The $1{\times}16$ thermo-optic switch is farmed as 4-stage which consists of 15 unit devices. The unit devices are the $2{\times}2$ thermo-optic switches with Mach-Zehnder interferometer(MZI) structure. The characteristics of the $1{\times}16$ thermo-optic switch depends strongly on each unit device. The unit deviceconsists of two 3-dB general interference MMI couplers and two single mode waveguide arms as a phase shifter. First of all, the 3-dB optical splitter and $2{\times}2$ MZI thermo-optic switch have been tested to confirm the characteristics of the unit devices of the $1{\times}16$ MZI thermo-optic switch. Using the measurement results of the unit devices, the $1{\times}16$ MZI thermo-optic switch can be produced with better characteristics. The resultant structure of the MMI coupler with the optical light source of wavelength of 1550nm for the $1{\times}16$ thermo-optic switch is that the width and the optimized length are $25{\mu}m\;and\;1580{\mu}m$, respectively. The smallest excess loss fur the unit device is -0.5dB and the average excess loss is -0.7dB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.05c
• /
• pp.21-23
• /
• 2004

We report experimental results demonstrating a novel metal defined polymer optical waveguide with a low loss in electro-optic polymers for the first time. The polymer optical waveguides are created using a metal film on the top of upper cladding without any conventional etching process. The fabricated waveguides have an excellent lateral optical mode confinement at both 1.31 ${\square}m$ and 1.55 ${\square}m$ wavelength, resulting in a fiber-to lens optical insertion loss of ~ 7 dB at 1.55 ${\square}m$ and ~4.5 dB at 1.31 ${\square}m$ wavelength in a 3.5cm total length for TM polarizations, respectively. We also present the optical loss dependence of the waveguide as a function of optical wavelengths. These results may be used in the complex design of integrated polymer optical circuits that need simpler and cheaper fabrication process.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.5A
• /
• pp.674-681
• /
• 2000

We proposed polymer based vertical asymmetric optical coupler. And we optimized the proposed device by coupling characteristic analysis In 1.33um wavelength, TE mode, we obtained very short coupling length(L=277.6um), high coupling efficiency(94%). The merits of proposed device are low propagation loss due to very short full device, low production cost and time, and high integrated fabrication. We will use this to fabricate optical switch, modulator and tunable WDM devices, etc.

• Korean Journal of Optics and Photonics
• /
• v.30 no.6
• /
• pp.249-254
• /
• 2019

An optical current sensor device that measures electric current by the principle of the Faraday effect was designed and fabricated. The polarization-rotated reflection interferometer and the quadrature phase interferometer were introduced so as to improve the operational stability. Complex structures containing diverse optical components were integrated in a polymeric optical integrated circuit and manufactured in a small size. This structure allows sensing operation without extra bias feedback control, and reduces the phase change due to environmental temperature changes and vibration. However, the Verdet constant, which determines the Faraday effect, still exhibits an inherent temperature dependence. In this work, we tried to eliminate the residual temperature dependence of the optical current sensor based on polarization-rotated reflection interferometry. By varying the length of the fiber-optic wave plate, which is one of the optical components of the interferometer, we could compensate for the temperature dependence of the Verdet constant. The proposed optical current sensor exhibited measurement errors maintained within 0.2% over a temperature range, from 25℃ to 85℃.

• 한국가시화정보학회:학술대회논문집
• /
• 2002.04a
• /
• pp.51-78
• /
• 2002

A number of research groups worldwide are studying electronic implants that can be mounted on retinal optic nerve/visual cortex to restore vision of patients suffering from retinal degeneration. The implants consist of a neural interface made of biocompatible materials, one or more integrated circuits for stimuli generation, a camera, an image processor, and a telemetric channel. The realization of these classes of neural prosthetic devices is largely due to the explosive development of micro- and nano-electronics technologies in the late $20^{th}$ century and biotechnologies more recently. Animal experiments showed promise and some human experiments are in progress to indicate that recognition of images can be obtained and improved over time. We, at NBS-ERC of SNU, have started our own retinal implant project in 2000. We have selected polyimide as the biomaterial for an epi-retinal stimulator. In-vitro and in-vivo biocompatibility studies have been performed on the electrode arrays. We have obtained good affinity to retinal pigment epithelial cells and no harmful effect. The implant also showed very good stability and safety in rabbit eye for 12 weeks. We have also demonstrated that through proper stimulation of inner retina, meaning vision can be obtained.