Robust optical systems using maximum likelihood sequence estimators

2005 ◽  
Author(s):  
S.J. Savory ◽  
A. Napoli ◽  
B. Thomsen ◽  
P. Bayvel ◽  
R.I. Killey
Keyword(s):  
Maximum Likelihood ◽  
Optical Systems

scholarly journals Maximum likelihood sequence detection in laser phase noise-impaired coherent optical systems

2011 ◽  
Vol 19 (23) ◽  
pp. 22600 ◽  
Author(s):  
Xuguang Shao ◽  
Pooi-Yuen Kam ◽  
Changyuan Yu
Keyword(s):  
Maximum Likelihood ◽  
Phase Noise ◽  
Optical Systems ◽  
Sequence Detection ◽  
Maximum Likelihood Sequence Detection

scholarly journals Maximum Likelihood Sequence Detection Receivers for Nonlinear Optical Channels

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Gabriel N. Maggio ◽  
Mario R. Hueda ◽  
Oscar E. Agazzi
Keyword(s):  
Maximum Likelihood ◽  
Channel Estimation ◽  
Fiber Optic ◽  
Matched Filter ◽  
Direct Detection ◽  
Polarization Mode Dispersion ◽  
Optical Systems ◽  
Sequence Detection ◽  
Maximum Likelihood Sequence Detection ◽  
The Impact

The space-time whitened matched filter (ST-WMF) maximum likelihood sequence detection (MLSD) architecture has been recently proposed (Maggio et al., 2014). Its objective is reducing implementation complexity in transmissions over nonlinear dispersive channels. The ST-WMF-MLSD receiver (i) drastically reduces the number of states of the Viterbi decoder (VD) and (ii) offers a smooth trade-off between performance and complexity. In this work the ST-WMF-MLSD receiver is investigated in detail. We show that thespace compressionof the nonlinear channel is an instrumental property of the ST-WMF-MLSD which results in a major reduction of the implementation complexity in intensity modulation and direct detection (IM/DD) fiber optic systems. Moreover, we assess the performance of ST-WMF-MLSD in IM/DD optical systems with chromatic dispersion (CD) and polarization mode dispersion (PMD). Numerical results for a 10 Gb/s, 700 km, and IM/DD fiber-optic link with 50 ps differential group delay (DGD) show that the number of states of the VD in ST-WMF-MLSD can be reduced ~4 times compared to an oversampled MLSD. Finally, we analyze the impact of the imperfect channel estimation on the performance of the ST-WMF-MLSD. Our results show that the performance degradation caused by channel estimation inaccuracies is low and similar to that achieved by existing MLSD schemes (~0.2 dB).

Atomic Resolution in Crystal Aperture Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 236-237
Author(s):  
J T Fourie
Keyword(s):  
Optical System ◽  
Spherical Aberration ◽  
Three Dimensional ◽  
Transmission Function ◽  
Optical Systems ◽  
Bragg Angle ◽  
Electron Optical System ◽  
Intimate Contact ◽  
Diffraction Effects ◽  
Design Aspect

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.

Maximum Likelihood for Social Science

2018 ◽  
Author(s):  
Michael D. Ward ◽  
John S. Ahlquist
Keyword(s):  
Maximum Likelihood ◽  
Social Science
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