The “mode-splitting” phenomenon based on whispering gallery mode (WGM) was observed in coupling resonators, which are composed of two size-mismatched microspheres. The wavelength separation and intensity of the two splitting peaks varied with changing sized discrepancy for coupling microspheres. As the size of the first microsphere was fixed and coupled with a tapered fiber, it’s shown that the wavelength separation of two splitting peaks increased firstly and then decreased with the increasing size of the size-varied microsphere coupled to the first. The maximal wavelength separation could be achieved for identical-sized microspheres, with a minimal difference for intensity also noted. This analysis could provide better application prospects in measurement for judging similar-sized microspheres and measuring the size of microspheres.
Fiber Bragg grating (FBG) extensively employed in a variety of ways. In this paper, we designed an FBG sensor structure and introduced a novel method to determine the angle of vibration source. The performance of our sensor and the method were validated through experiments. We placed the sensor in a controlled water tank environment, utilizing a spherical object to generate vibration as the vibration source to stimulate the sensor. Through the FBG wavelength shifting data, the angle of ball was determined by the method. The results showed that the average deviation was only3 degrees, with an accuracy rate of 90%. Our finding demonstrate that this novel sensor has a better perception capability for minor vibrations and the angle determination method for the vibrating object has excellent accuracy.
All-photon memory, holding significant potential for applications in optical communication systems and neural network computing, and developing an all-optical dual-channel fiber storage platform that achieves integrated storage and computation is challenging. In this paper, a non-volatile, high-contrast, and highly repeatable bipolar memory is demonstrated, achieved by integrating two tapered fibers with a fiber microsphere containing phase change materials(PCMs). Employing an external laser modulation technique, repeatable or randomly accessible 6-level data storage is enabled by altering the state of Ge2Sb2Te5 (GST). Multi-stage writing is accomplished using a 532 nm pump laser witha10 ns pulse width and laser energy ranging from 0.423 mJ to 1.206 mJ, while a 793 nm continuous wave (CW) laser with an average power of 4 mW to 11 mW is utilized for the multi-stage reset process. Exhibiting a write response time of 75ns, a reset response time of 180 ns, and a contrast of 18 dB, the bipolar memory preliminarily realizes the synaptic weight update mechanism in the synapse of neural network systems
Multi-level optical switches play an important role in all-photon communication networks. In this paper, we demonstrate an all-photonic non-volatile, quasi-continuous, multi-level optical switch which based on phase change material (PCM, Ge2Sb2Te5) and fiber micro-structure. With the help of 793nm CW laser and 532nm nanosecond pulse laser, this all-photon multistage optical switch can be operated repeatedly in six switching states. In multi-stage modulation, writing is realized by a 532 nm nanosecond pulsed laser with pulse energy of 1.426 mJ, and erasing is realized by a 793 nm CW laser with pulse powers from 4.2 to 9.6 mW. The experiment shows the optical switch has the advantages of high optical contrast (about 38%), repeatability and non-volatile (0.2dB). Hopefully, the all-photonic optical switch presented in this paper provides insights on optical computing and lays some experimental basis for all-photon information transmission.
We propose a gelatin-coated long period fiber grating humidity sensor which has temperature compensation for low-error humidity detection. The output spectrum shows three resonance dips. The dip caused by gelatin-coated grating has humidity sensitivity of 0.09 nm/%RH and temperature sensitivity of 0.15 nm/°C. Another two dips caused by PDMS-coated grating have almost no response to humidity, which can be used for temperature compensation under low temperature and high temperature range, respectively. We come up with a coefficient matrix and experimentally obtain the humidity and temperature sensitivity of both resonance dips, thus temperature and humidity can be demodulated.
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