Research On Photonic Integrated Devices For Physical Dimension Manipulation Of Light Fields

Light field has multiple physical dimension resources,including wavelength/ frequency,amplitude,phase,polarization,time and spatial structure,which have been widely used in various fields related to light.In the field of optical communications,to further improve the communication capacity of optical communication systems,wavelength division multiplexing(WDM)technology related to the wavelength dimension has been widely used,and the space-division multiplexing(SDM)/mode-division multiplexing(MDM)technology related to the spatial structure has also been regarded as a very promising solution.However,the traditional optical devices used to manipulate light fields have many disadvantages,such as single function,low-density integration,and lack of reconfigurability and tunability,which are not conducive to the flexible management of optical communication systems.In recent years,the emerging silicon-based photonic integration technology has rapidly developed,showing outstanding advantages such as CMOS compatibility and high-density integration,which has attracted wide interest,provided a new platform and better opportunity for the true integration of photonics and electronics,and greatly promoted the development of optoelectronic integration technology.In this thesis,we mainly focus on the researches on the manipulation of wavelength dimension,conventional waveguide mode and structured light field using photonic integrated devices.The major contents of this dissertation are summarized as follows:(1)The manipulation of the wavelength/frequency dimension based on silicon photonic integrated devices is studied theoretically and experimentally.(1)The tunable comb filter based on the Fabry–Pérot(FP)cavity is studied theoretically and experimentally.By adjusting the reflection and transmission coefficients of the Sagnac loop mirrors,the wavelength and bandwidth of the filter can be adjusted.(2)By controlling the coupling state between the microring resonator and the FP cavity,on-chip Fano resonance and Electromagnetically induced Transparency(EIT)effects are realized theoretically and experimentally.(3)Multi-functional processor is fabricated.By integrating two 16-channel arrayed waveguide gratings(AWGs)and 16 Mach-Zehnder interferometers(MZIs),the granularity-flexible programmable optical filter and reconfigurable optical add/drop multiplexer(ROADM)are successfully implemented.High-speed signal transmission using the fabricated device is demonstrated in the experiment.(4)Inspired by the concept of traditional electronic field programmable gate array(FPGA),an optical “FPGA” structure is designed and fabricated.The programmable ability of the device is demonstrated in the experiment,including various filters,delay line and optical switch.(2)The manipulation of conventional waveguide modes based on silicon photonic integrated devices is studied theoretically and experimentally.(1)A high-order mode multiplexer based on microring resonators is designed and fabricated.(2)The concept of Fano resonance is introduced into the field of modes,and multimode Fano resonance is proposed.Fano resonances for two modes are realized theoretically and experimentally,and the device is further applied to low-power mode switching process.(3)An on-chip fourmode(de)multiplexer in the mid-infrared band is designed and fabricated,and high-speed MDM communications using the fabricated chip are also demonstrated in the experiment.(3)The manipulation of structured light fields based on active and passive integrated devices is studied theoretically and experimentally.(1)Based on the compact annular grating structure,the detection of high-order vortex beams is studied theoretically and experimentally.(2)Through the special design of trench-assisted waveguide structure,the vortex beam generator and multiplexer are proposed and verified by simulations.(3)A highspeed directly modulated integrated vector beam laser is studied theoretically and experimentally.Based on the active microring resonator,single-mode lasing with high sidemode suppression ratio is realized by designing the second-order gratings on the top and sidewall of the microring resonator.The lasing mode is a cylindrical vector mode.In addition,the modulation speed of the fabricated directly modulated laser is up to 20 Gbit/s,and it is also applied to 2-km fiber vector eigenmode transmission.Meanwhile,the concentric ring resonator structure is proposed,which can be used in vector mode-based high-speed multiplexing communications.(4)Using the silicon photonic integration platform,a multidimensional photonic emitting array is designed and fabricated,which can dynamically and independently manipulate the spatial amplitude,phase and polarization of the light field.A 4×4 multidimensional photonic emitting array is fabricated.By the proper adjustment of more than 70 electrode control units,various complex light fields are generated in the experiment,including vortex beams with topological charges of ± 1 and ± 2,8 vector beams on the high-order Poincaré spheres,and more complicated vector vortex beams.