Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Optics and Photonics
Journal Basic Information
Journal DOI :
Optical Society of Korea
Editor in Chief :
Volume & Issues
Volume 19, Issue 6 - Dec 2008
Volume 19, Issue 5 - Oct 2008
Volume 19, Issue 4 - Aug 2008
Volume 19, Issue 3 - Jun 2008
Volume 19, Issue 2 - Apr 2008
Volume 19, Issue 1 - Feb 2008
Selecting the target year
Study on Sensitivity of Burst-Mode Optical Receiver Depending on Photodiode Capacitance
Lee, Jung-Moon ; Kim, Chang-Bong ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 343~348
DOI : 10.3807/HKH.2008.19.5.343
This study was carried out to commercialize FTTH by developing a burst mode optical receiver for E-PON. The optical receiver was manufactured by minimizing the capacitance of a photodiode to improve sensitivity for meeting 10, 20 km OLT Rx standard of E-PON at the transmission speed of 1.25 Gb/s. When bit-error ratio is
and PRBS is
, sensitivity is -26 dBm, loud/soft ratio is 23 dB. Both preamble time and guard time were set to 102.4 ns (128 bit). After comparing a photodiode whose capacitance is 0.53 pF with another photodiode whose capacitance has been minimized to 0.26 pF, we could see that sensitivity improved to 0.7 dBm and so did bandwidth to 190 MHz of burst mode for the optical receiver manufactured by the photodiode whose capacitance is 0.26 pF.
Ultra-Compact Zoom Lens Design for Phone Camera Using Hybrid Lens System
Park, Sung-Chan ; You, Byoung-Taek ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 349~359
DOI : 10.3807/HKH.2008.19.5.349
For an inner-focusing 3-groups zoom lens system, this study suggests a new initial design method which applies the process that changes thin lenses into thick ones effectively and quickly, using the hybrid lens system(thin lens+thick lens). In other words, the hybrid lens system is the semi-automatic design process that makes the thin lens of one group change into a thick one while the other groups are composed of thin lenses. Keeping the total power of the system fixed, the power of each group and the distance between principal planes can be fixed. Of course, the other groups composed of thin lenses could be changed into thick lenses sequentially by this process. This design conception results in the 1/4" 5 M inner-focusing 3-groups 2x zoom lens system satisfying the specifications and performances of zoom lens for phone cameras. Also aspherization on lens elements of glass and plastic material enhanced the resolution and reduced the lens size. As a result, we have an ultra-compact inner-focusing 3-groups 2x zoom lens system for a phone camera, with a slim size with TTL of 9.8 mm.
Analysis of Reconstructed Images of Computer Generated Hologram Formed according to Grating Modulation Methods
Jeong, Man-Ho ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 360~364
DOI : 10.3807/HKH.2008.19.5.360
The diffraction efficiencies of gratings are affected by the inner structure which is determined by modulation type. CGH (Computer generated Hologram) basically uses the principles of a diffraction grating. As like as the diffraction gratings the patterns recorded in the CGH are different according to modulation methods which result in the performances of the reconstructed images. In this paper, on this fact CGHs are recorded according to sinusoidal and rectangular modulation methods and the characteristics of reconstructed images are analyzed. Also the reconstruction performances of the amplitude and phase, phase-only and binary phase CGH are analyzed.
Characteristic Studies for Scan-Field Size and Visibility of Current Image in a Low Voltage Micro-Column
Noriyuki, Ichimura ; Kim, Young-Chul ; Kim, Ho-Seob ; Jang, Won-Kweon ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 365~369
DOI : 10.3807/HKH.2008.19.5.365
The optimal condition for focusing an electron beam was investigated employing an electrostatic deflector in a low voltage micro-column. At fixed voltage of the electron emission tip, the focusing electron beam with source lens showed a larger scan field size and poorer visibility than those with an Einzel lens. Theoretical 3-D simulation indicated that a focusing electron beam with a source lens should have a larger spot size and deflection than those of a focusing Einzel lens.
High-Speed High-Resolution Terahertz Time-Domain Spectrometer
Kim, Young-Chan ; Kim, Ki-Bok ; Yee, Dae-Su ; Yi, Min-Woo ; Ahn, Jae-Wook ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 370~375
DOI : 10.3807/HKH.2008.19.5.370
High-speed high-resolution terahertz time-domain spectroscopy (THz-TDS) is demonstrated using the asynchronous-opticalsampling (AOS) method. A time-domain signal with a 10-ns time window is rapidly acquired by using two femtosecond lasers with slightly different repetition frequencies to generate and detect a terahertz pulse wave, without a mechanical delay stage. The spectrum obtained by the fast Fourier transformation (FFT) of the time-domain waveform has a frequency resolution of 100 MHz. The time resolution of our spectrometer is measured using the cross-correlation method to be 278 fs. A transmission spectrum of water vapor is measured and the absorption lines are analyzed in the frequency range from 0.1 to 1.2 THz.
3D Precision Measurement of Scanning Moire Using Line Scan Camera
Kim, Hyun-Ju ; Yoon, Doo-Hyun ; Kim, Hak-Il ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 376~380
DOI : 10.3807/HKH.2008.19.5.376
This paper presents the Projection Moire method using a line scan camera. The high resolution feature of a line scan camera makes it possible to scan an image quickly, thus enabling a much quicker 3D profile. This method uses a high resolution line scan camera making it possible to scan an image at high speed simultaneously measuring the 3D profile of a large FOV. When using a high resolution scan camera, a full FOV is scanned, thus requiring just one movement of a projection grating. As a result, the number of grating movements is reduced drastically. The end result is a faster and more accurate 3D measurement. Moving the grating too quickly causes vibration in the imaging system, which will normally be required to apply a stitching technique when using an area scan camera. However the technique is not required when using a line scan camera. Compared with the previous techniques, it has the advantages of simple hardware without moving mechanical parts - single exposure for obtaining three-dimensional information. A method using a high resolution line scan camera can be used in mass production to measure the bump height of wafers or the bump height of package substrates.
Analysis of the Effect of the Substrate Removal and Chip-Mount Type on Light Output Characteristics in InGaN/Sapphire LEDs
Hong, Dae-Woon ; Yoo, Jae-Keun ; Kim, Jong-Man ; Yoon, Myeong-Jung ; Lee, Song-Jae ;
Korean Journal of Optics and Photonics, volume 19, issue 5, 2008, Pages 381~385
DOI : 10.3807/HKH.2008.19.5.381
We have analyzed the effect of the substrate removal and packaging schemes on light output characteristics in InGaN/Sapphire LEDs. The removal of the sapphire substrate helps to dissipate the heat generated in the junction, but the advantage comes only with the detrimental effect of degrading the photon extraction efficiency. If the substrate-removed chip is attached to a metallic mount with good thermal conductivity, the maximum driving current is increased drastically, producing significantly increased light output and therefore compensating the photon extraction efficiency degradation. On a dielectric mount with a relatively poor thermal conductivity, however, it produces smaller light output, over most input current range, than the regular type of chips with the sapphire substrate remaining. Thus, for low power applications, the regular chips may be preferred over the substrate-removed chips, regardless of the chip mounts employed.