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Dark-bright optical solitons conversion via an optical add/drop filter for signals and networks security applications
(2010-10-01)
Knobnob, B.
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Mitatha, S.
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Dejhan, K.
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Chaiyasoonthorn, S.
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Yupapin, P. P.
We propose a new system of the darkbright solitons conversion using a micro- and nano-ring resonators incorporating an optical add/drop filter, where the add/drop filter can be used to convert the dark soliton to bright soliton. The key advantage of the system is that the detection of the dark soliton pulse is normally difficult due to low level of input power. Firstly, a dark soliton pulse is input into a micro-ring resonator, then propagating into smaller micro- and nano-ring resonators. Secondly, the add/drop filter is applied (connected) into the ring system, where the bright and the dark solitons are obtained via the drop and through (or throughput) the ports of the add/drop filter, respectively. The results obtained have shown that the detected soliton power can be controlled by the input soliton power and the ring resonator coupling coefficient, which is enough to use in the transmission link. The optical and the quantum networks using dark soliton are also discussed. © 2009 Elsevier GmbH. All rights reserved.
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High-frequency log-domain current-mode multiphase sinusoidal oscillator
(2010-09-01)
Prommee, P.
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Sra-ium, N.
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Dejhan, K.
This study describes the design of a multiphase sinusoidal oscillator (MSO) based on log-domain filtering concept. The circuit is a direct realisation of a first-order differential equation for obtaining the inverting and non-inverting low-pass filters. Each low-pass filter comprises only a grounded capacitor and four transistors. The proposed MSO can be instantaneously controlled over a very wide frequency range by controlling the current for the oscillation frequency and oscillation condition which indicates the proposed MSO's suitability in high-frequency applications. A validated bipolar junction transistor (BJT) model is used in SPICE simulation operated from a single power supply as low as 2.5 V. The oscillation frequency is controlled over four decades of frequency. The total harmonic distortions for three phase (11.5 MHz) and four phase (7 MHz) are, respectively, obtained around 2.4 and 2.2% which enables them to be fully integrated in telecommunication systems. The power consumption is around 5.5 mW for 100 μA bias current. Moreover, experimental results of three-phase MSO are included. © 2010 The Institution of Engineering and Technology.
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Packet switching start-stop bits generation based on bifurcation behavior of light in a micro ring resonator
(2010-02-01)
Mitatha, S.
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Dejhan, K.
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Yupapin, P. P.
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Pornsuwancharoen, N.
This paper proposes the interesting nonlinear behavior of light known as bifurcation, where the use of such behavior in a micro ring resonator to form the secure digital codes for optical packet switching application is demonstrated. A new concept of the stop-start bits in an optical packet switching protocol is formed by using the bifurcation codes. Bifurcation is introduced when light is input into a nonlinear micro ring device, where the refractive index of an InGaAsP/InP is one of device parameters. The other parameters of the device are coupling coefficient (K) and the ring radius (R), where the ring radii used are ranged from 5 to 10 μm. Simulation results obtained have shown that the packet switching data can be secured by using the generated start-stop bits as the secured codes. © 2008 Elsevier GmbH. All rights reserved.
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Chaotic signal generation and coding using a nonlinear micro ring resonator
(2010-01-01)
Mitatha, S.
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Dejhan, K.
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Yupapin, P. P.
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Pornsuwancharoen, N.
We propose a new digital encoding method using light pulses tracing in a micro ring resonator, where the randomly digital codes can be performed. The chaotic signals can be generated and formed by the logical pulses "1" or "0" by using the signal quantizing method, which can be randomly coded by controlling the specific optical input coupling powers, i.e. coupling coefficient (κ) and ring radii. Simulation results when the ring radius used is 10.0 μm, and the other selected parameters are close to the practical device values that are presented and discussed. The random codes can be generated by the random control of coupling powers, which can be transmitted and retrieved via the design filters by the specific clients. For instance, the controlled input power used is between 2.0 and 3.5 mW, whereas the quantizing threshold powers and the traveling roundtrips are 0.3-0.4 mW and 8000-10,000, respectively. In application, the required information can be generated, and the information can be securely transmitted in the public link. © 2008 Elsevier GmbH. All rights reserved.
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High-capacity and security packet switching using the nonlinear effects in micro ring resonators
(2010-01-01)
Mitatha, S.
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Dejhan, K.
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Yupapin, P. P.
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Pornsuwancharoen, N.
We propose a new design of secured packet switching generated by using nonlinear behaviors of light in a micro ring resonator. The use of chaotic signals generated by the micro ring resonator to form the filtering and packet switching characteristics is described, where the high-capacity and security switching using such form is presented. The key advantage is that the high capacity of communication data can be secured in the transmission link, where the nonlinear penalty of light traveling in the device is beneficial. For instance, the required information can be transmitted and retrieved by using the proposed packet switching scheme. In principle, the chaotic signals are generated by a Kerr effects nonlinear type of light in a micro ring resonator, where the control input power can be specified by the required output filtering signals. The ring radii used range between 10 and 20 μm, κ=0.0225, α=0.5 dB and n<inf>2</inf>=2.2×10<sup>-15</sup> m<sup>2</sup>/W. Simulation results obtained have been described based on the practical device parameters. Three forms of the applications have been simulated, the potential of using for the tunable band pass and band stop filters, in which high-capacity packet switching data can be performed, and the fs switching time is plausible. © 2008 Elsevier GmbH. All rights reserved.
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New papr reduction in ofdm systems by hybrid algorithm of pts and appr methods
(2009-12-01)
Pradabpet, C.
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Yoshizawa, S.
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Miyanaga, Y.
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Dejhan, K.
In this paper, we propose a new peak to average power ratio (PAPR) reduction technique by a hybrid algorithm based on a partial transmit sequence (PTS) and adaptive peak power reduction (APPR) methods. This technique is used in a system based on orthogonal frequency division multiplexing (OFDM OFDM has orthogonally modulated sub-carriers which unexpectedly give large PAPR and tends to reduce the power efficiency of a RF amplifier. To reduce PAPR, the sequence of input data is rearranged by PTS for the reduction of PAPR and then fed to APPR process in the proposed system. The APPR method controls the peak level of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In simulation results, the proposed method shows the improvement on PAPR, PSD, and also the high performance on bit error rate of an OFDM system.
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Searching phase optimize in PTS-APPR method by GA for PAPR reduction in OFDM-WLAN systems
(2009-11-12)
Pradabpet, C.
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Yoshizawa, S.
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Miyanaga, Y.
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Dejhan, K.
In this paper, we propose a new PAPR reduction using the hybrid of a partial transmit sequences (PTS) and an adaptive peak power reduction (APPR) methods with genetic algorithm (GA). These methods are used in an Orthogonal Frequency Division Multiplexing (OFDM) system. The OFDM employs orthogonal sub-carriers for data modulation. These sub-carriers unexpectedly present a large Peak to Average Power Ratio (PAPR) in some cases. In order to reduce PAPR, the sequence of input data is rearranged by PTS. The APPR method is also used to controls the peak level of modulation signals by an adaptive algorithm. A proposed reduction method consists of these two methods and realizes both advantages at the same time. In order to make the optimum condition on PTS for PAPR reduction, a quite large calculation cost must be demanded and thus it is impossible to obtain the optimum PTS. In the proposed method by using genetic algorithm, the total calculation cost becomes drastically reduced. The parameter for simulation used standard WLAN in IEEE 802.11a system. In simulation results, the proposed method shows the improvement on PAPR and also reveals the high performance on bit error rate (BER) of an OFDM system. © 2009 IEEE.
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An efficient filter structure for multiplierless sobel edge detection
(2009-11-12)
Pradabpet, C.
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Ravinu, N.
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Chivapreecha, S.
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Knobnob, B.
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Dejhan, K.
This paper presents a multiplierless Sobel edge detection filter structure based on the gradient of Gaussian lowpass filter concept. This concept is same as the idea that used for evaluation of Sobel edge detection kernels. The proposed Sobel edge detection filter structure consists of 4 sets of the so-called lowpass-type 2nd order 1-D DPF (Discrete Pascal Filter) and the filter structure does not need any multipliers, only 14 adders are needed for realization. Consequently, the high efficiency multiplierless Sobel edge detector can be achieved. © 2009 IEEE.
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A new PAPR reduction technique for OFDM-WLAN in 802.11a systems
(2008-12-24)
Pradabpet, C.
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Eupree, K.
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Chivapreecha, S.
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Dejhan, K.
In this paper, we proposed a new PAPR reduction technique using selective mapping (SLM) cascade with adaptive peak power reduction (APPR) methods. This technique is used in a system based on Orthogonal Frequency Division Multiplexing (OFDM). OFDM has many orthogonally modulated sub-carriers which unexpectedly produce high peak to average power ratio (PAPR). The high PAPR will occasionally reach the amplifier saturation region and therefore result in signal distortion, which causes bit error rate (BER) degradation. The proposed method, a sequence of input data is rearranged by SLM for the reduction of PAPR and then fed into the APPR process in the proposed system. The APPR method controls the peak levels of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. The parameter for simulation used standard WLAN in IEEE 802.11a system. In simulation results, the proposed method shows the improvement on PAPR, power spectrum density(PSD) and high performance BER compared with conventional APPR. © 2008 IEEE.
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PAPR reduction in OFDM systems using SLM cascade with APPR methods
(2008-10-06)
Eupree, K.
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Chivapreecha, S.
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Dejhan, K.
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Pradabpet, C.
In this paper, we proposed a new PAPR reduction technique using selective mapping (SLM) cascade with adaptive peak power reduction (APPR) methods. This technique is used in a system based on Orthogonal Frequency Division Multiplexing (OFDM). OFDM has many orthogonally modulated subcarriers which unexpectedly produce a peak to average power ratio (PAPR) and tend to reduce the power efficiency of a RF amplifier. A sequence of input data is rearranged by SLM for the reduction of PAPR and then fed into the APPR process in the proposed system. The APPR method controls the peak levels of the modulation signal by an adaptive algorithm. It reduces modulation signals over a predefined range. In simulation results, the proposed method has shown better PAPR reduction compared to the SLM and the APPR. ©2008 IEEE.

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