氮化硅微腔中的光学频率梳(特邀)

具有高品质因子（Q 值）的光学谐振腔能够长时间将光束缚在较小的模式体积内,极大地增强了光与物质的相互作用,成为集成光学器件中具有重大潜力的重要组成部分。聚焦于目前广泛应用于集成非线性光学领域的氮化硅材料平台,为了解决大尺寸氮化硅微环腔由拼接误差、表面粗糙等因素导致的散射损耗较大的问题,进行了一系列的工艺改进以提高大尺寸氮化硅微环腔的品质因子。结果表明:通过薄膜再沉积工艺可以有效降低氮化硅波导的散射损耗,半径为560 μm的大尺寸氮化硅微环腔的本征Q值得到了平均26% 的提升。得益于提高的微腔Q 值,在氮化硅微环腔中实现了重复频率40 GHz 的光学频率梳。     

SiO2/W反射叠层的分布电容对体波谐振器的影响

该文使用SiO₂和金属材料钨（W）构造布喇格反射叠层,将其应用于由横向电场激励体声波谐振器（XBAR）,并分析了金属层对谐振器性能的影响。所设计的谐振器以128°YX-切铌酸锂为压电层,Al为电极,SiO₂和W为周期层叠结构,单晶硅作为衬底的固态装配型谐振器（SMR）,利用叉指电极换能器（IDT）激发出A1模式。首先计算声阻抗层厚度对SiO₂/W叠层传输系数的影响,得到中心频率为3.7 GHz的布喇格阻带。横波（主模）在经过叠层时被反射,纵波（杂模）则部分地泄露到衬底。由于钨具有电导性,致使IDT与钨之间形成并联分布电容,改变了原有的电场分布,导致谐振器的耦合系数下降。通过实验测试谐振器的实际性能,获得耦合系数为12%。虽然W具有高声阻抗,但分布电容的影响恶化了电气参数。     

Low-power thermooptical tuning of SOI resonator switch

A wavelength selective optical switch is developed based on a high-Q racetrack resonator making use of the large thermooptic coefficient of silicon. The racetrack resonator was fabricated using a silicon-on-insulator (SOI) single-mode rib waveguide. The resonator shows a high Q factor of 38 000 with spectral sidelobes of 11 dB down and can be thermooptically scanned over its full free-spectral range applying only 57 mW of electrical power. A low power of 17 mW is enough to tune the device from resonance to off-resonance state. The device functions as a wavelength selective optical switch with a 3-dB cutoff frequency of 210 kHz.     

Dielectric Resonator Antenna on Silicon Substrate for System On-Chip Applications

This paper presents for the first time the design and performance of a novel integrated dielectric resonator antenna fabricated on a high conducting silicon substrate for system on-chip applications. A differential launcher to excite the ${rm TE}_{01delta}$ mode of the high permittivity cylindrical dielectric resonator was fabricated using the IBM SiGeHP5 process. The proposed antenna integrated on a silicon substrate of conductivity 7.41 S/m has an impedance bandwidth of 2725 MHz at 27.78 GHz, while the achieved gain and radiation efficiency are 1 dBi and 45% respectively. The design parameters were optimized employing Ansoft HFSS simulation software. Very good agreement has been observed between simulation and experimental results. The results demonstrate that integration of dielectric resonator antennas on silicon is viable, leading to the fabrication of high efficient RF circuits, ultra miniaturization of ICs and for the possible integration of active devices.      

Silicon micromachined EBG resonator and two-pole filter with improved performance characteristics

A novel micromachined resonator at 45 GHz based on a defect in a periodic electromagnetic bandgap structure (EBG) and a two-pole Tchebyshev filter with 1.4% 0.15 dB equiripple bandwidth and 2.3 dB loss employing this resonator are presented in this letter. The periodic bandgap structure is realized on a 400 /spl mu/m thick high-resistivity silicon wafer using deep reactive ion etching techniques. The resonator and filter can be accessed via coplanar waveguide feeds.     

基于微机械圆盘谐振器的振荡器

基于微机械谐振器的硅振荡器是微波通信系统中的关键器件。制作了工作于径向体声学振动模态的微机械谐振器,通过分析微机械谐振器的电参数,并以此谐振器为基础进行振荡器的设计。针对圆盘形微机械谐振器工作过程中阻抗较大的问题,通过多级放大来补偿信号经过谐振器时引起的衰减和相位变化。振荡器包括两部分放大电路,基本振荡回路的多级放大保证振荡器正常起振,输出多级放大保证振荡器的输出达到一定的功率。所设计的振荡器阻抗44kΩ,振荡频率143.33MHz,为大阻抗条件下振荡器的设计提供一定的参考。     

Ultrafast Relaxation of Charge Carriers Induced Switching in Terahertz Metamaterials

We demonstrate ultrafast switching of resonant mode in terahertz metamaterials through optical excitation of radiation-damaged silicon placed in the gap of a split-ring resonator. Upon optical excitation, we observe the dynamic transition of the fundamental resonance from ON-to-OFF state on a timescale of 4 picoseconds (ps) and then fast recovery of the resonance to the ON-state within the next 20 ps. Electric field distributions in the metamaterial unit cell derived through numerical simulations clearly support our experimental observations, showing that the high electric field at the resonator gaps, responsible for inductive-capacitive (LC) resonance, completely disappears and switches OFF the resonance after being optically excited. The ultrafast switching of the metamaterial resonance is attributed to the relaxation of the photo-carriers through the defect states of radiation-damaged silicon layer. Such ultrafast material–based active control of metamaterials can lead to the ultrafast terahertz metaphotonic devices.     

A 5 kW CW CO2 laser using a novel negative-branchunstable resonator with a phase-unifying output coupler

A 5 kW CW CO₂ laser using a negative-branch unstable resonator (M=-1.5) is proposed and characterized experimentally. The resonator consists of a stepwise variable reflecting output coupler, called the phase-unifying output coupler, and a total reflector. A 5 kW CW laser beam with diffraction limited quality (2&thetas;=0.45 mrad) is obtained and affected by the focal point in the resonator. The misalignment angle to reduce the laser power to 95% is improved by a factor of 19 compared with a positive-branch unstable resonator (M=1.5) with a phase-unifying output coupler at the same resonator length     

Stabilisation of optically excited self-oscillation

A new experiment demonstrating the stabilisation of an optically driven self-oscillator is reported. The oscillation of the micromechanical silicon resonator is maintained by optical feedback provided by a Fabry-Perot interferometer formed between a semireflecting mirror and the surface of the silicon micromechanical resonator. The stabilisation of the oscillation is achieved by adjusting the frequency of the laser diode powering the system.<>     

一种MEMS体声波硅谐振器的设计

设计了一种基于SOI衬底工艺的MEMS体声波硅谐振器及其制造方法。利用有限元分析软件对该谐振器进行了模态分析,并针对提高品质因数Q,研究了其损耗机制。结果表明：谐振频率可达108MHz,且取决于硅材料特性和器件尺寸,而品质因数则决定于支撑损耗。最后,从振动模态和传输线模型角度出发,提出了减少支撑损耗提高Q值的可行性方法,包括将支撑梁放置在振动节点处、梁长度设置为弹性波长的1/4及在衬底端设置声波反射器。     

Experimental results of a high Q quasioptical reflection cavity

A quasi-optical reflection cavity intended to be used as the resonant load of a submillimeter wavelength oscillator has been designed, constructed, and tested. The resonator consists of three elements in cascade: a high Q, high finesse folded Fabry-Perot resonator, a lower Q, low finesse Fabry-Perot resonator, and a Littrow mounted diffraction grating. The resonator exhibits a Q of 6600 and 2.5 dB of loss at 63 GHz. The design can be scaled to 1 THz, where waveguide structures become impractical, to serve as the resonator for high frequency quantum well resonant tunneling device oscillators.     

Reference SAW oscillator on quartz-on-silicon (QoS) wafer forpolylithic integration of true single chip radio

The authors present an electro-acoustic circuit fabricated on quartz directly bonded on the processed silicon wafer (QoS), which allows us to polylithically integrate high precision passives with integrated circuits. We first fabricated a prototype SAW resonator and oscillator on thick QoS. The SAW resonator on QoS shows Q about 10,000 and 11 dB insertion loss at 289 MHz, and SAW oscillator on QoS shows phase noise of as small as -120 dBc at 100 kHz offset, demonstrating the feasibility of true single chip radio     

基于阳极键合的硅微圆盘多环谐振陀螺的设计与制作

提出了一种新型的基于阳极键合的硅微圆盘多环谐振陀螺的结构设计及其制作方法.该种陀螺采用MEMS工艺制作而成,基底材料为肖特BF33玻璃,电极和谐振器均由单晶硅片加工而成,肖特BF33玻璃与单晶硅片通过阳极键合工艺键合在一起.介绍了该种陀螺的基本结构、工作原理,并进行了仿真分析,得出该种陀螺具有较小的频率分裂,表现出陀螺效应.最后,通过MEMS工艺进行了实际加工,得到了该种陀螺的实验样品.     

Ring resonator fabricated in phosphosilicate glass films deposited by chemical vapor deposition

The design and fabrication of a closed loop (ring) resonator is described. The resonator was fabricated in phosphosilicate glass films deposited by chemical vapor deposition onto oxidized silicon substrates. A channel waveguide-to-channel waveguide tapered mode directional coupler was used to transfer light from the input channel to the ring. To our knowledge this is the first demonstration of the use of such a coupler for coupling between channel waveguides. An analysis is presented for power distribution in the channels of the coupler, for stored, reflected and transmitted powers in the resonator and for resonator finesse. Operation of the resonator was demonstrated experimentally and finesse values of less than 3, comparable to those published elsewhere in the literature, were obtained.     

A W-Band Air-Cavity Filter Integrated on a Thin-Film Substrate

In this letter, a W-band air-cavity filter has been developed on a thin-film substrate using a lossy silicon substrate as a base plate, which is suitable for a mm-wave system-on-package. The lossy silicon suppresses a parasitic substrate mode excited in a thin-film substrate, while a coupling loss between a transmission line and a resonator is minimized by etching the backside of the lossy silicon substrate underneath the coupling area. In the backside etching process, 70 mum of silicon was left for mechanical support of the thin-film substrate. The resonator was fabricated using a low-cost silicon micromachining technique and was flip-chip integrated on a thin-film substrate. The fabricated air-cavity resonator showed an unloaded Q of 851 at a resonant frequency of 94.18 GHz. Improvement in the coupling loss by the backside etching process was verified with measurement results. The fabricated filter exhibited an insertion loss of 1.75 dB and a return loss better than 14.5 dB with a 1.3% 3 dB fractional bandwidth at a center frequency of 93.8 GHz.     

A 1.6-GHz Current-Controlled Oscillator with Integrated Inductor

A 1.6 GHz fully monolithic silicon bipolar LC current-controlledoscillator (CCO) circuit implemented in a 0.8 µmBiCMOS technology and characterized for use in wireless applicationsis presented. The integrated resonator circuit uses high speed(18 GHz) bipolar transistors, a 14 nH rectangular spiral inductorfabricated by using a standard 2-level metallization, and a widebandpn-varactor structure. Additionally, to save chip area, the integratedcapacitors were fabricated below the planar inductor structure.In order to aid the IC design, a simple equivalent circuit modelfor the integrated inductor on silicon was developed and tested.The measured quiescent power dissipation of the integrated CCOcircuit is 1.9 mW to 5.5 mW from a supply of 2–;3 V, anda typical phase noise varies from –82 to –86 dBc/Hz at 100 kHz offset.     

A Single-Crystal-Silicon Bulk-Acoustic-Mode Microresonator Oscillator

A timing reference incorporating a single-crystal-silicon micromechanical resonator with a quality factor of larger than one million and a resonant frequency of 2.18 MHz is demonstrated. The resonator is excited in the square extensional bulk acoustic mode at 4 mtorr, and it has been fabricated in a foundry SOI MEMS process. The silicon microresonator is adapted as a timing element for a precision oscillator with a measured short-term Allan deviation of 0.6 ppb.      

Highly efficient convolution computing architecture based on silicon photonic Fano resonance devices

Convolutional neural networks (CNNs) require a lot of multiplication and addition operations completed by traditional electrical multipliers, leading to high power consumption and limited speed. Here, a silicon waveguide-based wavelength division multiplexing (WDM) architecture for CNN is optimized with high energy efficiency Fano resonator. Coupling of T-waveguide and micro-ring resonator generates Fano resonance with small half-width, which can significantly reduce the modulator power consumption. Insulator dataset from state grid is used to test Fano resonance modulator-based CNNs. The results show that accuracy for insulator defect recognition reaches 99.27% with much lower power consumption. Obviously, our optimized photonic integration architecture for CNNs has broad potential for the artificial intelligence hardware platform.     

Thermally tunable integrated optical ring resonator with poly-Sithermistor

Doped polysilicon is applied as a thermo-optic heating element to temperature tune the ring resonator based on silicon nitride rib waveguides on silicon. The ring diameter is 2 mm allowing a large free spectral range of 26 GHz. For the first time, a poly-Si resistor is used as a thermistor to measure waveguide temperature. The temperature coefficient of the poly-Si thermistor is 9.5×10^-4/°C. The reproducibility of the temperature measurement is 0.3°C. The finesse of the ring resonator is 77. The propagation loss of silicon nitride rib waveguide is 0.5 dB/cm at the wavelength of 1.312 μm. The temperature tuning of the ring resonator and the in situ supervision of the temperature on chip based on the same poly-Si fabrication process may find use especially in optical sensor applications     

A micromechanical analogue mixer with dynamic displacement amplification

A new micromechanical device is proposed which is capable of modulation, demodulation and filtering operations. The device uses a patented 3-mass coupled micromechanical resonator which dynamically amplifies the displacement within a frequency range of interest. Modulation can be obtained by exciting different masses of the resonator with the data and the carrier signals. Demodulation can be obtained similarly by exciting the actuator with the input and carrier signals at the same time. With the help of dynamic motion amplification, filtering and signal amplification can be achieved simultaneously. A generic design approach is introduced which can be applied from kHz to MHz regime frequencies of interest. A sample mixer design for an silicon on insulator-based process is provided. A SPICE (Simulation Program with Integrated Circuit Emphasis)-based electro-mechanical co-simulation platform is also developed and the proposed mixer is simulated.