• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.60-67
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• 2008

An all-optical 4-bit Gray code to binary coded decimal (BCD) converter by means of commercially available numerical analysis tool (VPI) was demonstrated, for the first time to our knowledge. Circuit design approach was modified appropriately in order to fit the electrical method on an all-optical logic circuit based on a cross gain modulation (XGM) process so that signal degradation due to the non-ideal optical logic gates can be minimized. Without regenerations, Q-factor of around 4 was obtained for the most severely degraded output bit (least significant bit-LSB) with 2.5 Gbps clean input signals having 20 dB extinction ratio. While modifying the two-level simplification method and Karnaugh map method to design a Gray code to BCD converter, a general design concept was also founded (one-level simplification) in this research, not only for the Gray code to BCD converter but also for any general applications.

• Journal of the Optical Society of Korea
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• v.6 no.4
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• pp.165-171
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• 2002

By using a semiconductor optical amplifier and a cross-phase modulation wavelength converter, fundamental all-optical logic gates including NOT, AND, NOR, XOR, and XNOR have been newly proposed and implemented. Realization of these all-optical logic gates will bring up not only all-optical networks but also all-optical computing and signal processing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1580-1584
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• 2009

We have theoretically analyzed the monolithic integration of vertical cavity lasers with depleted optical thyristor (VCL-DOT) structure and experimentally demonstrated optical logic gates such as AND-gate, OR-gate, and INVERTER implemented by VCL-DOT for an optical programmable gate array. The optical AND and OR gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity, high slope efficiency and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process. The fabricated devices clearly show nonlinear s-shaped current-voltage characteristics and lasing characteristics of a low threshold current with 0.65 mA and output spectrum at 854 nm.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.477-484
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• 2014

In this paper, we propose a new optical secret key sharing method based on the Diffie-Hellman key exchange protocol required in cipher system. The proposed method is optically implemented by using a free-space interconnected optical logic gate technique in order to process XOR logic operations in parallel. Also, we present a compact type of optical module which can perform the modified Diffie-Hellman key exchange for a cryptographic system. Schematically, the proposed optical configuration has an advantage of producing an open public key and a shared secret key simultaneously. Another advantage is that our proposed key exchange system uses a similarity to double key encryption techniques to enhance security strength. This can provide a higher security cryptosystem than the conventional Diffie-Hellman key exchange protocol due to the complexity of the shared secret key. Results of numerical simulation are presented to verify the proposed method and show the effectiveness in the modified Diffie-Hellman key exchange system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.10
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• pp.1591-1597
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• 1989

Through the matematical alaysis of EX-NOR logic relation between the input vector and the memory matrix, we propose a new method for optical implementation of the bipolar Hopfield neural network model based on the optical vector-matrix multiplier.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.150-151
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• 2001

광컴퓨터에 있어서 비선형 물질의 역할은 매우 중요하다. 그러한 비선형 물질들은 빛과 상호작용하고 빛의 성질을 변조시킨다. 광컴퓨터의 몇몇 구성 성분들은 그들이 작용하는데 있어서 중요한 비선형물질을 필요로 한다. 하지만 모든 광학적 장치들의 사용이 사실상 제한되는 것은 현재 이용할 수 있는 비선형 광물질이 비효과적이고 응답과 스위칭에 대해서 많은 에너지를 필요로 하기 때문이다. (중략)

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.492-499
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• 1997

We proposed and studied an all-optical switching device made of a bent nonlinear waveguide and an all-optical logic gate made of a bent nonlinear Y-junction. The proposed devices as switch and a logic function are based on the evolution of nonlinear guided wave along a bent nonlinear waveguide. Since the characteristics of beam propagation depens on the nonlinearity, input power and bent angle of waveguide, the characteristics of output power transmission is calculated by variation the such parameters. Furthermore, by calculating the output power through the nonlinear media with different positions of detector in nonlinear media, we could find the ideal digital switching performance at specific position of detector and implement several all-optical logic functions (AND, OR, XOR) by power contrast between waveguide end and nonlinear media.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.262-270
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• 2013

In this paper, we propose a modified optical CBC(Cipher Block Chaining) encryption method using optical XOR logic operations. The proposed method is optically implemented by using dual encoding and a free-space interconnected optical logic gate technique in order to process XOR operations in parallel. Also, we suggest a CBC encryption/decryption optical module which can be fabricated with simple optical architecture. The proposed method makes it possible to encrypt and decrypt vast two-dimensional data very quickly due to the fast optical parallel processing property, and provides more security strength than the conventional electronic CBC algorithm because of the longer security key with the two-dimensional array. Computer simulations show that the proposed method is very effective in CBC encryption processing and can be applied to even ECB(Electronic Code Book) mode and CFB(Cipher Feedback Block) mode.

• Journal of the Korea Computer Industry Society
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• v.3 no.2
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• pp.149-158
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• 2002

This paper deals with design and verification of an arithmetic logic unit(ALU) to be used for development of optical computers. The ALU is based on optical switching device, $LiNbO_3$, which is easy to interface with electronic technology and most common in the market. It consists of an arithmetic/logic circuit performing logic operations, memory devices storing operands and the results of operations, and supplementary circuits to select instruction codes, and operates in bit-serial manner. In addition, a simulator is developed for verification of the design, and a set of basic instructions are executed in sequence and step-by-step changes in the accumulator and the memory are examined through simulations, to show that various operations are performed correctly.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.42-43
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• 1999