We focus on the working environment of the mine based on the fiber grating sensing theory because of its passive, high-sensitivity and small-sized fiber grating as the front-end sensing unit to realize the integration and miniaturization of mine sensors. The structure of the sensor has been designed and analyzed according to the differential compensation methods. The differential dynamic temperature compensation algorithm can effectively eliminate the influence of temperature on the pressure detection by using the temperature-strain cross-sensitivity of the fiber grating. The temperature sensitivity is 31pm/°C, and the pressure sensitivity is 298 pm/Mpa with optimization. It can well realize the accurate measurement of various environmental parameter information in the process of coal mining, and fully reflect the superiority of the fiber sensor in the application of the coal mine engineering.
We review space-division multiplexing passive optical networks (SDM-PONs) based on multi-core fibers (MCFs) and few-mode fibers (FMFs). We compare and analyze the characteristics in terms of MCFs and FMFs used in PONs. A scheme of MCF based SDM-PON with colorless ONUs without any signal processing technology is demonstrated, thereby achieving a low cost and making the system design much easier.
It is very critical to improve the tracking stability in inter-satellites optical communication. The definition of the far-field light correlation efficient as been proposed, and the mathematical model that between it and divergence angle of tracking beacon has been established due to correlation of bidirectional beams. The results showed that the light intensity in the far-field is decreasing and dispersing with an increasing divergence angle, but not has an increasing far-field light correlation.
In this paper, we compare and analyze some schemes of generating the optical frequency comb. We propose a flexible and low-cost broadband optical frequency comb for dense wavelength-division multiplexing passive optical network (DWDM-PON) system by using a CW laser and electro-optic modulators followed by a dispersion flattened high nonlinear fiber (DF-HNLF). The frequency spacing and center wavelength of the frequency comb can be flexibly adjusted by changing the radio-frequency signal and the output wavelength of a continuous-wave (CW) laser, respectively.
The tracking is mainly used to maintain the established optical communication links (OCLs) in pointing, acquisition and tracking (PAT) ensuring the reliability of date transmission. The structure of pointing and tracking assembly, implementation methods and performances of beacon detector are reviewed. Analysis results show that reducing beam divergence and emission power, using closed-loop composite axis structure tracking system, removing acquisition beacon, analyzing far-filed characters of bidirectional tracking beam are critical to achieve high reliability of data transmission and long steady tracking in free-space optical communication.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.