Study On The Novel Silicon-based Integrated Photonic Devices

Continuously-emerged service requirement of human being,well-developed optical communication techniques and gradually-discovered application fields greatly boost the research and development of integrated photonic devices.Optical switching or routing systems are confronted with big challenges by the large-capacity and high-bit rate optical communication networks.Moreover,integrated optical devices gained wide-spread application in industry,military,energy,medicine,sensor,etc.To tailor the needs in different application fields,the device design strides forward to a common goal "Simpler, Smarter,Smaller,Swifter,and Saving energy & cost".Recently,researches on both the active and passive devices with silicon-on-insulator (SOI) material were underway and became a hot point in opto-electronics.Before successfully solving the bottleneck of micro-electronics,passive silicon devices still faced plenty of challenges:how to effectively evade or utilize the polarization in waveguide;how to realize a compact,low-crosstalk and broad-band optical switches;whether the photonic devices can implement the similar logic function to the electronic counterparts;how to tackle with the hybrid integration of silicon and the other useful materials,and so on.By employing the self-imaging(SIM) theory in optical waveguide,this thesis is intended to explore new schemes in the above spirit for optical devices with novel function, relaxed fabrication,easy controlling way and high performance.The basic physical effects in simple silicon devices are demonstrated by our own fabrication and CMOS foundry.The innovation of this thesis can be organized as four points:1.The SIM theory in many respects was deepened and extended.The SIM theory was generalized to the polarized mode issue,which results in a novel polarization rotator. The SIM phenomena in finite waveguide arrays were discussed by taking the secondary-neighborhood coupling into account.Light propagation in infinite waveguide arrays were investigated under different input conditions.The analytical model is established by combining the separate variable method and perturbation method to simplify spatial waveguide system.The design procedure of coarse wavelength division multiplexer (CWDM) based on the four-waveguide system is also illustrated.2.Several devices based on SIM theory are proposed,with merit in function,size and the controlling style.Taking the 3×3 MMI coupler as the basic element,this thesis proposed the easy-controlled ultra-compact 1×3 optical switch,2~3bit optical logic coder,a re-arrangeable six-port optical circulator.By using the multiplier relations of the modulation magnitudes for different switching state,1×N multi-valued controlled MMI switch was proposed to simplify the electrodes and controlling schemes.The method was therotically applied to steer light into spatial logic patterns with multimode waveguide.3.The basic units of the above-mentioned devices are systematically designed and demonstrated in silicon by using the CMOS industry and our own fabrication condition. By using 0.8μm CMOS line and the p-i-n carrier injection structure,the extinction ratios of the fabricated modulators can reach about 20dB.The crosstalks of the 1×2 and 2×2 MMI-based switches are 18dB and 17dB respectively.The device speed is about at the scale of tens of ns.Through fitting the experimental transmission curves,the performance limits to the Mach-Zehnder interferometric(MZI) switch crosstalk are systematically evaluated.In our lab,the inductively coupled plasma(ICP) reactive ion etcher was put into use after the parameter optimization.The fabrication techniques of the thermo-optical devices are also explored.4.Nonreciprocal silicon devices are conceived by numerically analyzing the magneto-optical Ce:YIG/Si/SiO2 waveguide.The perturbation method was used to observe the advantages of the Ce:YIG/Si/SiO2 structure in producing nonreciprocal phase shift (NPS).The 3-D semi-vector BPM formula are deduced and utilized to take the magneto-optical(MO) effect into account.NPS is introduced into micro-ring resonator to miniaturize the nonreciprocal device and improve the device performance.Besides, bi-directional multi-wavelength interleaved isolator is also proposed to favor the wavelength division multiplexing(WDM) system,by employing the Ring-coupled MZI structure.This thesis is related to multiple research directions,including the numerical calculation,device proposal and fabrication techniques.Partial work of these proposals and their demonstration are still underway.The author tries to carry out the above-stated "5S" spirit in the whole thesis and put forward several integrated optical devices with novel function and performance,which can be expected to facilitate the OEIC in the near future.