Simultaneous Optical Signal Research Articles

Multi-Task Learning Convolutional Neural Network and Optical Spectrums Enabled Optical Performance Monitoring

We propose a simultaneous optical signal recognition (OSR) and optical signal-to-noise ratio (OSNR) monitoring method by using multi-task learning convolutional neural network (MTL-CNN) in conjunction with optical spectrums, which enables optical performance monitoring (OPM) in the optical transmission network. In order to achieve a trade-off between monitoring loss and time consumption of the MTL-CNN constructed for seven commonly used signals with a spectrum resolution of 10 pm, the number of feature map channels in four convolutional layers is delicately designed as 32, 32, 64, and 64 with task weights set to 0.4 and 0.2, corresponding to OSNR monitoring and OSR, respectively. Simulation results manifest that this method can realize the recognition of the received optical signals with an overall accuracy of 100% and also enable OSNR monitoring with the mean absolute error (MAE) of 0.262 dB. The proposed method shows strong robustness to various distortions and exhibits good performance in terms of time consumption. The effectiveness is further verified by proof-of-concept experiments in three signals. These illustrate that our method is a promising solution for multi-parameter monitoring with high accuracy and efficiency.

Simultaneous optical signal to noise ratio and symbol rate estimation with blind chromatic dispersion compensation for auxiliary amplitude modulation optical signals

Based on the peak to valley ratio (PTVR) of the average magnitude difference function (AMDF), we present a novel optical signal to noise ratio (OSNR) and symbol rate (SR) estimation method for commonly used auxiliary amplitude modulations (AAMs). Moreover, it is demonstrated that the influence of chromatic dispersion (CD) on the method can be mitigated by maximizing the PTVR of the AMDF with additional tunable dispersion compensators. The results of simulations show that the OSNR estimation error can be kept within 0.8 dB in the wide OSNR range of (12, 32) dB, while the SR estimation error is below 0.079% for four widely used 10 Gsymbol/s AAM signals.

Simultaneous Optical Signal Sampling for Orthogonal Components of Optical Phase Shift Keying Signals with Bidirectional Use of a Chirped Periodically Poled LiNbO<sub>3</sub> Wavelength Converter

Simultaneous Optical Signal Sampling for Orthogonal Components of Optical Phase Shift Keying Signals with Bidirectional Use of a Chirped Periodically Poled LiNbO<sub>3</sub> Wavelength Converter

Combined Multimodal Optical Imaging and Targeted Gene Silencing Using Stimuli-Transforming Nanotheragnostics

Combined diagnosis and therapy for cancer has been of great interest in medicine. Small interference RNA (siRNA)-encapsulating polyplexes were covalently coated with small gold nanoparticles (Au NPs) via acid-cleavable linkages in order to explore the possibility of achieving combined stimuli-responsive multimodal optical imaging and stimuli-enhanced gene silencing. In a mildly acidic tumor environment, Au NPs are dissociated from the siRNA-carrying polyplexes, generating various optical signal changes such as diminished scattering intensity, increased variance of Doppler frequency, and blue-shifted UV absorbance (stimuli-responsive imaging). Simultaneously, Au NP dissociation exposes the siRNA-carrying polyplex with elevated surface charge and results in enhanced cellular uptake and transfection (stimuli-enhanced therapy). In this study, the feasibility of achieving combined diagnosis and therapy for cancer (theragnostics) is demonstrated by (1) microscopic and spectrophotometric confirmation of acid-transformation of the nanoparticles, (2) reduced scattering intensity and increased variance of Doppler frequency in an acidic pH upon the nanoparticle's transformation, and (3) simultaneous optical signal changes and gene silencing in vitro under a tumor pH-mimicking condition. This novel type of stimuli-responsive nanotheragnostics will provide a new paradigm for pinpointed, multimodal, and combined imaging and therapy for cancer.

基于光纤中四波混频效应光逻辑门的信号同步提取与擦除

基于光纤中四波混频效应光逻辑门的信号同步提取与擦除

LOTIS: GRB follow-up observations at early times

LOTIS is an automated wide field-of-view telescope system capable of responding to GRB events as early as 10 s after a trigger from the GCN which rapidly distributes coordinates from the BeppoSAX, BATSE and RXTE instruments. Measurements of optical activity at these early times will provide important clues to the GRB production mechanism. In over two year's of operation, LOTIS has responded to 40 GCN triggers including GRB 971227 within 10 s and GRB 980703 within 5 hours. We report results from these events and constraints on simultaneous optical signals during these GRBs.

Dc point-to-plane discharge in pure oxygen in the 50-760 Torr pressure range

The present work is a part of a general study dealing with pure gases at pressures in the 50-760 Torr range. This experimental study concerns discharges occurring in oxygen, between a curvature radius rhodium point and a stainless steel plane 1 cm distant. A positive dc high voltage is applied to the point using a 0-30 kV, 0-10 mA power supply. Electrical measurements are performed so that voltage-current characteristic curves can be drawn for the whole pressure range. Current impulses are recorded at the earthed plane in each typical regime of the discharge. These electrical impulses are compared with the simultaneous optical signals obtained from a photomultiplier. A focalization on the photomultiplier of various precise spots in the interelectrode gap allows one to get some information about the propagation of an ionizing front from the high-voltage electrode to the grounded plane. From comparison with previous studies, it may be inferred that the glow regime is more difficult to visualize on the characteristic curves than it is in the case of nitrogen. However, `streamer-like' impulses are observed for oxygen in the whole pressure range, which is not the case for nitrogen. The continuity between these streamer-like impulses and the `classical' streamers observed at atmospheric pressure seems to be established and confirms the important role played by electronegativity in the inception of ionizing fronts.

Fiber-optic microwave link with monolithic integrated optoelectronic up-converter

An efficient and simple method for simultaneous optical signal detection and subcarrier generation in a fiber optic radio system is demonstrated. Baseband signals are transmitted from a central station through optical fiber to a base station where the signals are up-converted to a higher subcarrier frequency for sufficient radiation. This has been achieved with the use of a monolithic integrated metal semiconductor metal photodetector (MSM-PD) and MESFET optoelectronic up-converter. >

Optical observations of X-ray bursts from MXB 1837 + 05

Optical observations of the X-ray burst source MXB 1837 + 05 (Ser X-1) made at different observatories are discussed. Six X-ray bursts were detected with SAS-3 during these observations, but no simultaneous optical signals were seen during or after any of these bursts. For an assumed burst duration of 10 s, the 3σ upper limits of the ratio of the detected energy in an optical burst to that in an X-ray burst range from 3 × 10−5 to 6 × 10−5.