Electromagnetically Induced Transparency/absorption-like Effect In Silicon-on-insulator Based A Coupled Microring System

With the high level integration of microelectronic devices,traditional electronic devices have been unable to meet the high requirements for data transmission rate and bandwidth.The silicon-based optoelectronic devices is widely used in many important fields,such as optical communications,optical storage,optical interconnect and so on by virtue of its low production cost,fast transmission rate,high transmission bandwidth,and CMOS compatibility,antielectromagnetic interference and so on.Silicon-based coupled micro-ring resonator is one of the most important silicon-based optoelectronic devices.In recent years,Electromagnetically induced transparency / absorption-like(EIT / EIA-like)effect found in silicon-based coupled micro-ring resonators has gradually become a hotspot.EIT / EIA-like effect causes a light isn't absorbed,which should be absorbed,and will make the light group speed plummeted,or even 0,result in a strong slow light effect,which can be used for light delay and cache to achieve all-optical storage.In addition to slow light,the EIT / EIA effect can be used in the fields of optical switches,optical sensors,nonlinear optics,quantum information processing.At the same time,compared with EIT / EIA effect in the atomic system,EIT / EIA-like effect does not require harsh experimental conditions,resulting in a more extensive application that of EIT / EIA effect.In this paper,we have presented a ring-bus-ring-bus(RBRB)system on a silicon-oninsulator(SOI)platform where two resonators are coupled via an asymmetric 3×3 coupler and experimentally demonstrated EIT/ EIA effects in this configuration for the first time.At the same time,the theoretical analysis and experimental study are carried out on the micro-ring resonator.The main contents are as follows:(1)The temporal coupled-mode theory is employed to model and analyze the all-pass filter,the add-drop filter,the RBRB geometry,and the corresponding theoretical model is established.The influence of the resonant wavelength and the coupling loss rate between ring and bus on the structural characteristics of the single ring and the RBRB geometry is analyzed.Taking into account the direct coupling and indirect coupling of the double rings.Under the influence of the direct coupling of the double rings,the resonant wavelength of the double rings is not exactly the same,but slightly different,when the EIT / EIA effect occurs.And the simulation results show that the direct coupling coefficient of the double rings is negative.(2)A series of RBRB structures with rings' radius of about 5?m were fabricated.The parameters of the low-Q ring were kept constant.When the distance between the high-Q and intermediate waveguides was different,the high-Q ring radius is slightly tuned to change resonant wavelength difference between two rings.Finally,the EIT and EIT-like effects are observed in the through port and drop port.When the high-Q ring is in the over-coupling regime,With the increase of the distance between the high-Q ring and the intermediate waveguide,the extinction ratio of resonant peak of the high-Q ring will increase,the transmission and bandwidth of the EIT-like window decreases,Q factor obviously increases,the maximum Q factor can be up to about 9000.The all-pass filters are also fabricated on the same chip of RBRB systems.The experimental results show that the resonant wavelength increases as the radius increases,and the fitting slope(??/?R)is 0.753.(3)The RBRB structures with rings' radius of about 10?m was fabricated where the heater was added above the high-Q ring.Resonant wavelength difference between two rings is arbitrarily adjusted by adjusting the power of the heater.Finally,the EIT-like effect was obtained.The relationship between the distance between the high-Q and intermediate waveguides and the output spectrum is the same as that of the conventional RBRB.The maximum Q factor of the EIT-like window can be up to about 17,000.At the same time,the apparent Fano line appears on the right side of transmission spectra,and it is proved that the direct coupling of the double ring can not be neglected and the direct coupling coefficient between the two resonant modes of our RBRB structure is negative.The experimental results show that the resonant wavelength increases as the heater power increases,and the power efficiency of the thermo-optic tuning(??/?P)is 0.273 nm/mW.