1,720,979 research outputs found
Optical CDMA system with the least multiple access interference under arbitrary restrictions
No full textThe most important issue in asynchronous optical code division multiple-access (CDMA) systems is the multiple access interference (MAI), which is caused by the non-ideal orthogonal property of optical codes and which is the main factor of the bit error. In this paper, we propose and examine an extremely versatile optical code, the adaptive resonance code (ARC), which has the least MAI under arbitrary restrictions arising from designing optical CDMA systems. The analytical results show that ARC has near-ideal MAI and that the available number of nodes in a system is doubled without changing the coding scheme and/or physical structure of the system at the cost of little performance degradation. In the traditional method of implementing an optical CDMA system, components such as optical sources and encoders/decoders are designed after choosing an optical code. When ARC is used, it is also possible that components are first designed with their own specialties and then an optimal code set for the components is generated. (C) 2003 Elsevier B.V. All rights reserved
1 x 3 wavelength demultiplexer based on multimode interference with an indexmodulation region
No full textWe propose a novel structure for a compact 1 x 3 wavelength demultiplexer with an index-modulation region incorporated into a multimode interference coupler. We can have an extra output port with a simple device structure. The performance of this device has been enhanced by changing the phase within the region. (C) 2004 Wiley Periodicals, Inc
An ultra compact 1x2 wavelength demultiplexer based on multimode interference with an index-modulation region
No full textIn this paper, we propose a novel structure for an ultra-compact wavelength demultiplexer with an index-modulation (IM) region incorporated into a multimode interference coupler. The device length can be reduced by using asymmetric output ports and the performance of this device has been enhanced by changing the phase within the region. (C) 2004 Wiley Periodicals. Inc
Feed-forward control of transient gain dynamics of an EDFA for optical burst networks
No full text,In this letter we demonstrate a technique for suppression of transients in output bursts of an erbium-doped fiber amplifier (EDFA) in an optical burst network To suppress the transients, the EDFA is forward-fed by non-fluctuating input utilizing a power-modulated burst control packet channel. Using the technique, we obtained a maximum 1.7 dB reduction in gain transient in the EDFA output, and we transmitted 9 953 Gbps data bursts and 2.488 Gbps burst control packets stably
An optical code with the least multiple access interference under arbitrary restrictions for optical CDMA systems
No full textThis work was
supported in part by KOSEF through OIRC
Wavelength mismatch tolerance in wavelength-hopping and time-spreading optical CDMA systems
No full textThe autocorrelation peak reduction due to wavelength mismatches between an encoder and a decoder in wavelength hopping-time spreading (WH-TS) two-dimensional optical CDMA systems is analyzed and verified by experiments. The tolerance of the wavelength mismatch is then obtained through the analysis of the system bit error rate (BER) performance. The results show that no significant BER performance is degraded only by the wavelength mismatches less than 0.1 nm which corresponds to 25 percent of the typical fiber Bragg gratings' spectral width
PLC-type variable optical attenuator operated at low electrical power
No full textA novel voltage-controlled variable optical attenuator based on a polymeric planar lightwave circuit (PLC) is demonstrated. The fabricated variable attenuator shows 30dB attenuation with only 80mW electrical input power at 1.55 mum. The polarisation dependences at 0 and 10dB attenuations are 0.2 and 1dB, respectively. The rise and fall times are less than 5ms
Very low crosstalk 1 x 2 digital optical switch integrated with variable optical attenuators
No full textA novel digital thermo-optic switch based on a polymer waveguide has been demonstrated. The proposed switch consists of a conventional 1x2 digital optical switch and compact variable optical attenuators. with both elements: integrated in series. The switches exhibit very low crosstalk values of -42 and -40d8, and the switching power is similar to 170mW at 1.55 mum
Polymer waveguide thermo-optic switches with - 70 dB optical crosstalk
No full textTo reduce the crosstalk of the polymer waveguide optical switches, waveguide attenuators are integrated with the switch on the same substrate. The switch and attenuator shares a single connected electrode which is controlled by a single current source. Due to the simple structure of the integrated attenuator, the device length is reduced to 10 mm so as to provide low insertion loss of 0.8 and 1.1 dB for 1300 and 1550 nm, respectively. Further radiation of the remained optical signal on the switch-off branch is induced by the integrated attenuator so that the switching crosstalk is reduced to -70 dB with an applied electrical power of 200 mW. The low crosstalk is maintained for the environmental temperature range of -10 to 55 degrees C. (c) 2005 Elsevier B.V. All rights reserved
An all-optical gain-controlled amplifier for bidirectional transmission
No full textA novel all-optical gain-controlled (AOGQ bidirectional amplifier is proposed and demonstrated in a compact structure. The AOGC function using fiber Bragg grating (FBG) pairs controls both directional signals independently, and combinations of optical interleavers and isolators suppress Rayleigh backscattering (RB) noise. The amplifier achieves high and constant gain with a wide dynamic input signal range and low noise figure. The performance does not depend on the input signal conditions, whether static-state or transient signals, or whether there is symmetric or asymmetric data traffic on bidirectional transmission. Transmission comparison experiments between invariable symmetrical and random variable asymmetric bidirectional data traffic verify that the all-optical gain control and bidirectional amplification functions are successfully combined into this proposed amplifier.I wish to thank the Photonics Research Laboratory, in the
Department of Electrical and Electronic Engineering, The
University of Melbourne, Australia, for their help
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