Photodetectors And Optical Microring Resonator With SU-8 Structure

The integrated photonic devices attract more and more interest of researchers due to its high compactness and miniaturization.Among most integrated optical materials such as SiO2,Si,InP,lithium niobite,Si3N4 and polymer materials,polymer shows great potential in optical waveguides due to cost reduction,low loss and large bandwidth.The mid-infrared wavelength range,which covers from 2 to 20 micrometers,is critical for a number of application areas,including chemical bond spectroscopy,thermal imaging,pharmaceuticals,forensic,security and safeguard,astronomy,climate and pollution monitoring,sensing and detection of some prominent gases,liquids and solids.In this paper,based on SU-8 polymer material and the absorption in visible light range of silicon,we design and fabricate a photodetector array for detecting the angle of the incident light.Since Si can work as detector material during visible wavelength,the thickness of SU-8(200nm?20?m)can be controlled well and the fabrication process is simple,in this paper an angle detector array based on MSM structure with simple structure and high feasibility is presented.During the fabrication process,we find and finally solve the problem about the poor repeatability of dark current when we fabricate the 'Isolated Island' detector.With the modification,the detector we fabricated covers the angle range from-45 ? to 45 ?,the dark current is 1.5uA@1V and the responsibility is 0.7mA/W.What's more,in the 2 ?m wavelength range,we design and fabricate the SU-8 waveguides and MRRs to explore the application prospect of SU-8 polymer material for the mid-infrared range.With Lumerical software,the functionality of the SU-8 waveguide in the 2 ?m wavelength range is simulated.The accurate parameter of the polymer waveguide is given and the relationship between the bending loss and the bending radius of the SU-8 waveguide is calculated.MRR(Microring Resonator)with coupling area based on s-bend structure is designed and fabricated.UV lithography is used here to fabricate the chip due to its low manufacturing cost and simple technology.The fabrication process and the test platform are given in detail in this paper which covers growing film,glue dilution,spin coating,prebaking,UV lithography,post baking,developing,hard baking,cleavage and vertical coupling.The calculated loss for vertical coupling is about 6 dB and the propagation loss in the 2 ?m wavelength range is about 15 dB/cm according to truncation method.Besides,the extinction ratio of the MRRs is about 3dB and FSR(Free Space Range)is about 1.3 ?m,which agrees well with the simulation.