Research On On-chip Temperature Sensing Characteristics Based On GaAs Microdisk Resonator

The whispering gallery mode(WGM)optical microcavity is widely used in the fields of nonlinear optics,optical communication and high sensitivity sensor because of its high-quality factor and small mode volume.Among them,highly sensitive temperature sensing has an important influence on the performance of integrated photon devices and biological information detection.Therefore,high performance on-chip based temperature sensor is very important.Gallium arsenide(GaAs)is a kind of direct band gap materials with excellent luminescent properties in the near infrared region and can be used to realize integrated photon circuit,biosensor and so on However,there are few reports on the temperature sensing based on GaAs microdisk resonators.In this paper,we focus on the research of temperature sensing characteristics of on-chip GaAs microdisk cavity-based sensor.Through process optimization,device preparation,performance test and experimental verification,we have realized the high-sensitivity temperature sensor based on GaAs micro-disk resonator,which has the potential in the field of on-chip micro cavity temperature sensor.The main studies included have been shown as follows,1.Based on WGM theory,three key characteristic parameters of WGM microcavity,namely,Q value,effective mode volume and free spectrum range,are introduced.The mode field distribution of WGM is studied.And three states of waveguide microcavity coupling are studied by coupling mode theory including under coupling,critical coupling and over coupling2.By optimizing the fused tapered fiber,prepared the tapered fiber with low loss and easy coupling,realized the microwave photon filter with ultra-narrow linewidth and high peak suppression ratio by using the prepared straight taper-fiber coupled microsphere resonator,and combined with modulation technology;By optimizing the ring beating and annealing process,the fiber-taper helices have been fabricated with low loss,easy replication,easy coupling,and low parasitic coupling loss.The experimental results show that the transmittance of the fiber-taper helices is 97%3.By optimizing the refluxing process,gas etching process and post-processing cleaning technology,the WGM microdisk with considerable performance is prepared Using the optical coupling platform,the total Q-value(Qtot)of 10 ?m microdisk with the optical mode of 1.5225 ?m was 5 × 104,the corresponding FSR was 14.51 nm,and the coupling efficiency reached 94%when using the fiber-taper helices to couple the GaAs microdisk4.The temperature sensing principle and performance of WGM microcavity is studied in theory and experiment.The characteristics of WGM temperature sensor are simulated by model building and numerical simulation.The results show that the temperature sensitivity of GaAs microdisk increases linearly with the resonance wavelength,but is not sensitive to the radial mode number p and radius r.The temperature sensor with sensitivity of 0.142 nm/K and sensing resolution of 0.01K is realized,which can meet the needs of biological detection and integrated optical path temperature detection.And the phenomena of mode shift,broadening and thermal effect are verified.The results show that the high and low step phenomenon formed by scanning two modes under high light power is the result of the combination of the blue shift caused by the thermal nonlinear effect and the red shift caused by the thermal optical effect.