High-accuracy and high-speed optoelectronic oscillator (OEO)-based magnetic field and electric current fiber measurement is presented in this paper. Thanks to the Giant-Magnetoresistance Effect and Faraday Effect, the magnetic field and electric current can be transformed to the changes in characteristics of light propagating in optical fiber. Then, the use of OEO can translate the magnetic field and electric current dependent changes in optical domain to the oscillating frequency changes in microwave domain in order to increase the interrogation speed and resolution. The theoretical analysis and principle are investigated systematically. Experimental results are then provided to validate the OEO-enabled magnetic field and electric current measurement techniques.
A width-tunable optical pulses generation scheme by using a single Mach–Zehnder modulator (MZM) based on polarization-sensitive feature of LiNbO3 crystal is proposed and experimentally demonstrated. In the proposed system, a continuous-wave light is sent into MZM via a polarization controller (PC), and interference in a polarization beam splitter after passing through another PC. Experimental results show that the full-width at half-maximum of pulses (10 GHz) can be tuned continuously from 20.39 to 53 ps by adjusting the DC bias voltage of MZM and PCs. A 40 to 10 Gbit / s optical time division multiplexing (OTDM) signal demultiplexing experiment has been demonstrated using the time window provided by the proposed scheme. And the results show that the proposed width-tunable optical pulses generation scheme can be used in OTDM demultiplexing.
KEYWORDS: Modulation, Receivers, Detection and tracking algorithms, Digital signal processing, Phase shift keying, Signal detection, Signal processing, Optical networks, Networks, Process modeling
Abstract-In digital coherent optical receivers for various polarization-multiplexed high-order modulation formats such as BPSK、QPSK、8PSK and 16QAM signals, we propose and investigate a blind modulation format recognition method using the Chinese Restaurant Process, a kind of Dirichlet model, which is based on the observation of samples in Stokes space. The recognition rates of different number of data points under different optical signal-to-noise ratios (OSNRs) are investigated in detail for four modulation formats. In addition, the recognition characteristics of the proposed method are compared with other format recognition methods in Stokes space. It is shown that the approach has a better performance with higher recognition rates, particularly under a lower OSNR.
We propose and simulate numerically a permittivity-tunable metamaterial channel, which is composed of alternating layers of graphene and silica. The real part of the permittivity of the proposed metamaterial can be tuned from a positive value to a negative one for a broadband width. Furthermore, optical waves can pass through the metamaterial channel only when its permittivity is tuned to zero. Inspired by this intriguing property of the graphene–silica metamaterial, three basic electro-optical logic gates, including NOT, NOR, and NAND gates, were proposed and numerically investigated by using the finite element method. Taking advantage of the permittivity-tunable property of graphene, the working wavelength of the proposed electro-optical logic gates can be actively controlled by tuning the external voltage applied on the graphene–silica metamaterial. These tunable and ultracompact electro-optical logic gates could benefit the development of nanoscale optical devices for highly integrated photonic circuits.
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