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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 17, Issue 6 - Dec 2006
Volume 17, Issue 5 - Oct 2006
Volume 17, Issue 4 - Apr 2006
Volume 17, Issue 2 - Apr 2006
Volume 17, Issue 3 - Mar 2006
Volume 17, Issue 1 - Feb 2006
Selecting the target year
Beat Frequency Switchable Dual-mode External cavity laser
Kim, Chul-Seop ; Kim, Ryun-Kyung ; Lee, Kyung-Shik ; Song, Jeong-Hwan ; Oh, Yun-Kyung ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 489~492
DOI : 10.3807/KJOP.2006.17.6.489
We demonstrate a beat frequency-Switchable dual-mode external cavity laser hybrid integrated on planar lightwave circuit with an FP-LD and a sampled grating as external reflector. The dual-mode external avity laser was able to switch its beat frequency from 132GHz to 406GHz by changing LD current from 50mA to 55mA.
Analysis of Hollow Optical Fiber with Graded-Index Profile
Pee, Joong-Ho ; Jeong, Woo-Jin ; Kim, Chang-Min ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 493~499
DOI : 10.3807/KJOP.2006.17.6.493
Arbitrary graded-index HOF(Hollow Optical Fibers) are analyzed using the modified Airy function, and the corresponding eigenvalue equation that renders precise results is derived. For graded index HOF, the gradient of an evanescent field in hollow region could be adjusted more sharply than the conventional step-index HOF and the feasibility of more effective atom-guiding is confirmed.
Design Model of Intensity Modulation Type Displacement sensor Using Step-index Multimode Optical Fiber
Shin, Woo-Cheol ; Hong, Jun-Hee ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 500~506
DOI : 10.3807/KJOP.2006.17.6.500
An optical fiber displacement sensor has the advantages of relatively simplicity, cheap, small probe size and immunity against environmental perturbation. The working principle of the sensor is based on the intensity modulation that is detection light intensity reflecting from the surface being measured. This paper presents the mathematical model of displacement measurement mechanism of this sensor type. The theoretical and experimental data are compared to verify the model in describing the realistic approach to sensor design. Finally, the analysis results show that displacement response characteristics such as sensitivity, measuring range are easily modified by principal design parameters such as magnitude of optical Power, diameter of optical fiber core and distance between transmitting fiber and receiving fiber.
Image Encryption and Decryption System using Frequency Phase Encoding and Phase Wrapping Method
Seo, Dong-Hoan ; Shin, Chang-Mok ; Cho, Kyu-Bo ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 507~513
DOI : 10.3807/KJOP.2006.17.6.507
In this paper, we propose an improved image encryption and fault-tolerance decryption method using phase wrapping and phase encoding in the frequency domain. To generate an encrypted image, an encrypting key which denotes the product of a phase-encoded virtual image, not an original image, and a random phase image is zero-padded and Fourier transformed and its real-valued data is phase-encoded. The decryption process is simply performed by performing the inverse Fourier transform for multiplication of the encrypted key with the decrypting key, made of the proposed phase wrapping method, in the output plane with a spatial filter. This process has the advantages of solving optical alignment and pixel-to-pixel mapping problems. The proposed method using the virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting from unauthorized people and also can be used as a current spatial light modulator technology by phase encoding of the real-valued data. Computer simulations show the validity of the encryption scheme and the robustness to noise of the encrypted key or the decryption key in the proposed technique.
Highly Stable RF Transfer over a Fiber Network by Fiber-induced Phase Noise Cancellation
Lee, Won-Kyu ; Yee, Dae-Su ; Kim, Young-Beom ; Kwon, Taeg-Yong ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 514~518
DOI : 10.3807/KJOP.2006.17.6.514
We have transferred highly stable 100 MHz RF through a 23 km fiber network. The fiber-induced phase noise due to the vibration and the temperature fluctuation in the optical path is detected and is compensated by configuring a noise-canceling servo. The transfer instability was
at 1 s of averaging time and
at 10000 s of averaging time. The single sideband phase noise was greatly reduced by more than 20 dB below the Fourier frequency of 1 kHz. The transferred RF has nearly the same stability as the original reference frequency.
A Study on Lohmann Type Computer Generated Holograms Using a Circular Cell
Seo, Choon-Su ; Jeong, Man-Ho ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 519~524
DOI : 10.3807/KJOP.2006.17.6.519
In general, the Lohmann-type binary hologram represents its amplitude and phase by using the rectangular cell. In this paper, we adapts a circular cell to represents the amplitude and phase of holograms. In order to compare the characteristics of the circular cell with the rectangular one, we analyzed the results based on the computer simulations and various optical experiments. The results show that a clearer reconstructed image can be obtained by dividing one cell into many pixels. In the case of a uniform reconstructed image, the rectangular cell is better than the circular cell. However, as for the brightness of the reconstructed image, the circular cell is better than the rectangular one.
A Study on Three-Dimensional Computer Generated Holograms by 3-D Coordinates Transformation
Ryu, Won-Hyeon ; Jeong, Man-Ho ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 525~531
DOI : 10.3807/KJOP.2006.17.6.525
Synthesized 3-D CGH of a general three dimensional object is obtained by using a new 3-D coordinates transformation technique. A CCD camera is used to record several projected images of the 3-D object from different viewing angles. The recorded data are numerically calculated and processed to yield two-dimensional complex functions, which are then encoded fer the final synthesized 3-D CGH.
The Method for Estimating Stereoscopic Object Position with Horizontal-Moving Camera
Lim, Young-Tae ; Kim, Nam ; Kwon, Ki-Chul ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 532~536
DOI : 10.3807/KJOP.2006.17.6.532
The position of stereoscopic objects is an important parameter to induce three-dimensional effects such as convergence control and image distortions. There are three kinds of stereoscopic cameras : Parallel, Toed-in, and Horizontal-Moving cameras. In this paper we proposed the method for estimating stereoscopic object position with a horizontal-moving camera. In the previous methods, viewing angle ratios are used to estimate the object positions. Our method based on the horizontal movements of the camera to estimate the positions. Using geometrical models of shooting and display we experimented with two methods. Results of experiments showed the distance of stereoscopic objects on virtual screen related to horizontal movement.
A Method for Estimating a Distance Using the Stereo Zoom Lens Module
Hwang, Eun-Seop ; Kim, Nam ; Kwon, Ki-Chul ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 537~543
DOI : 10.3807/KJOP.2006.17.6.537
A method of estimating the distance using single zoom camera limits a distance range(only optical axis) in field of view. So, in this paper, we propose a method of estimating the distance information in Stereoscopic display using the stereo zoom lens module for estimating the distance in the wide range. The binocular stereo zoom lens system is composed using a horizontal moving camera module. The left and right images are acquired in polarized stereo monitor for getting the conversion and estimating a distance. The error distance is under 10mm which has difference between optically a traced distance and an estimated distance in left and right range
at center. This presents the system using a function of the zoom and conversion has more precise distance information than that of conversion control. Also, a method of estimating a distance from horizontal moving camera is more precise value than that from toe-in camera by comparing the error distance of the two camera methods.
Wide Tuning and Modulation Characteristics Analysis of Coupled-Ring Reflector Laser Diode
Yoon, Pil-Hwan ; Kim, Su-Hyun ; Chung, Young-Chul ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 544~547
DOI : 10.3807/KJOP.2006.17.6.544
A time-domain modeling approach is used to study characteristics of a widely tunable coupled-ring reflector (CRR) laser diode(LD). The CRR consists of a bus waveguide and two coupled ring resonators coupled to the bus without resorting to distributed Bragg grating structure. The tuning range can be a few tens of nanometers with a side mode suppression ratio exceeding 35dB through the adjustment of currents into the phase control sections in the rings. The CRR laser diode has long effective cavity length compared to conventional laser diodes. Accordingly, a broad additional resonance peak in the amplitude modulation characteristics is observed between 20 to 30 GHz, implying the extension of amplitude modulation bandwidth.
Effect of the Reflectivity of Both Facets and the Phase of a Phase Tuning Section on the Yield Characteristics of a Multisection Index-Coupled DFB Laser
Kim, Tae-Young ; Ryu, Jong-In ; Kim, Boo-Gyoun ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 548~555
DOI : 10.3807/KJOP.2006.17.6.548
We investigate the effect of the reflectivity of both facets and the phase of a phase tuning section on the self-pulsation (SP) characteristics of multisection index-coupled (IC) DFB lasers composed of two index-coupled DFB sections and a phase tuning section between them in terms of yield. In the case of weak coupling strength, as the reflectivity of both facets increases, the effect of reflected fields from both facets and the other DFB section on the mode characteristics of one DFB section increases. Thus the number of mode hoping increases and yield decreases for the variation of phases of both facets. In the case of strong coupling strength, as the reflectivity of both facets increases, the spatial hole burning effect increases, so that the yield decreases. The maximum yield and the range of the phase of a phase tuning section with yield more than 40% decrease as the facet reflectivity increases irrespective of coupling strength. As the coupling strength increases, the variation of yield for the variation of the phase of a phase tuning section increases and the variation of the phase of a phase tuning section with the maximum yield for the variation of the reflectivity of both facets decreases. The yield characteristics of the cases with the coupling strengths of 2 and 3 are better than those with the coupling strengths of 1.2 and 4.
Kilohertz Gain-Switched Ti:sapphire Laser Operation and Femtosecond Chirped-Pulse Regenerative Amplification
Lee, Yong-In ; Ahn, Yeong-Hwan ; Lee, Sang-Min ; Seo, Min-Ah ; Kim, Dai-Sik ; Rotermund, Fabian ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 556~563
DOI : 10.3807/KJOP.2006.17.6.556
We present a comprehensive study of a chirped pulse Ti:sapphire regenerative amplifier system operating at 1 kHz. Main constituents of the system are described in detail. The amplifier stage was first converted to a repetition rate-tunable kHz gain-switched nanosecond Ti:sapphire laser. Operation characteristics at different repetition rates such as build-up times of laser pulses, pump power-dependent output powers and pulse durations, damage thresholds, and tunability ranges were studied. Based on the results achieved, the switching time of the Pocket's cell used and the round trip numbers in the regenerative amplifier were optimized at 1 kHz. The output pulses with a pulse width of 50fs from a home-made Ken lens mode-locked Ti:sapphire oscillator were used as seed pulses. The pulses were expanded to 120ps in a grating stretcher prior to coupling into the 3-mirror amplifier cavity. After amplification and recompression, a stable 1kHz Ti:sapphire regenerative amplifier system, which delivers 85-fs,
pulses, was fully constructed.
Design and Demonstration of All-Optical XOR, AND, OR Gate in Single Format by Using Semiconductor Optical Amplifiers
Son, Chang-Wan ; Yoon, Tae-Hoon ; Kim, Sang-Hun ; Jhon, Young-Min ; Byun, Yung-Tae ; Lee, Seok ; Woo, Deok-Ha ; Kim, Sun-Ho ;
Korean Journal of Optics and Photonics, volume 17, issue 6, 2006, Pages 564~568
DOI : 10.3807/KJOP.2006.17.6.564
Using the cross-gain modulation (XGM) characteristics of semiconductor optical amplifiers (SOAs), multi-functional all-optical logic gates, including XOR, AND, and OR gates are successfully simulated and demonstrated at 10Gbit/s. A VPI component maker^TM simulation tool is used for the simulation of multi-functional all-optical logic gates and the10 Cbit/s input signal is made by a mode-locked fiber ring laser. A multi-quantum well (MQW) SOA is used for the simulation and demonstration of the all-optical logic system. Our suggested system is composed of three MQW SOAs, SOA-1 and SOA-2 for XOR logic operation and SOA-2 and SOA-3 for AND logic operation. By the addition of two output signals XOR and AND, all-optical OR logic can be obtained.