| Optical switching devices based on chalcogenide-based phase change materials have the advantages of short response time,non-volatility,low signal crosstalk and support for all-optical operation.The introduction of such optical switches into optical fibers can expand the applications of optical fibers in various fields such as all-optical control,optical storage and optical computing.However,the conditions under which phase changes in chalcogenide-based phase change materials occur are demanding,and it is difficult to modulate the phase state of chalcogenide-based phase change materials using fiber-optic guiding modes.Therefore,there has been little research on chalcogenide-based phase change materials in optical fibers,and no method has been proposed to couple chalcogenide-based phase change materials with optical fibers to form stable and efficient optical fiber devices.To solve the above problems,a tapered optical switch based on Ge2Sb2Te5（GST225）is proposed in this paper.The tapered optical fiber is used as the basic structure of the optical switch,and the strong absorption of laser light by the chalcogenide-based phase change material GST225 is used to design an all-optical operation-based GST225 phase modulation method.The feasibility of all-optical phase modulation of GST225 on a tapered fiber was verified using simulations.An optical switch structure with a high degree of coupling between GST225 and the guided mode of the fiber and a more consistent spectral response was prepared.An experimental system integrating optical signal generation,optical switching action and signal processing was designed and built according to all the requirements needed for the experiments.The optical switch is acted upon using a variety of light pulses with gradually varying parameters,and it is found that increasing the power and pulse width of the light pulses can effectively increase the optical contrast of the optical switch.There is an upper limit to this increase,and an unlimited increase in the optical pulse parameter will not further improve the performance of the optical switch,but will reduce the switching repeatability of the device,so that two optical pulse parameters（75 m W/10 ns and 30 m W/100 ns）can be used.The performance of the optical switch was tested and the proposed optical switch was able to achieve an optical contrast of 40%with a high switching repeatability and a response time of 80 ns（"0"to"1"state）versus 200 ns（"1"to"0"state）and operates in the C-band（1530 nm-1565 nm）for communications.The eight-state output optical switch is implemented using a reset method and is capable of storing3 bits of data in two steps（two optical pulses）.This paper investigates the optical switching application of GST225 on tapered fibers,realizing the modulation of the phase state of the phase change material GST225 by the fiber guide mode and extending the application of optical switching in the field of data storage.A new data processing and storage function is given to optical fibers,providing a new way of thinking for all-optical communication and sensing applications. |
