Millimeter-Wave Lange Coupler Design and Its Application in the Monolithic Image Rejection Mixer Design

This paper reports on the design of a Ka-band monolithic Lange coupler and its application in the monolithic fourth-harmonic image rejection mixer. Detailed design and analysis using Ansoft-HFSS simulator have been carried out. The simulated results of the Lange Coupler show the insert loss is better than −3.64 dB; the amplitude balance is less than 0.55 dB and the phase balance is less than 0.65° from the 90° phase difference over the 30 to 40 GHz frequency range. The Lange Coupler is employed in a monolithic image rejection mixer that is fabricated by a commercial 0.18-μm pseudomorphic high electron-mobility transistor (pHEMT) process. The chip size is 1.4 mm × 1.9 mm. The image rejection ratio (IMR) is from 15 to 34 dB in the RF frequency range of 30 to 40 GHz.     

Design of Ka-band Monolithic Image Rejection Mixer

In this paper, a 30–40 GHz monolithic image rejection mixer is described. The mixer employs two drain LO injection mixer cells, which can perform well even with zero drain bias voltage. Also it employs Lange Coupler for RF quadrature signal generation. The mixer is fabricated by a commercial 0.18-μm pseudomorphic high electron-mobility transistor (pHEMT) process. It achieves image rejection ratio of more than 20.4 dB and conversion loss of less than 12.6 dB in the frequency range of 30 to 38 GHz.     

Ka Band Broadband Fourth Harmonic Image Rejection Mixer

This paper presents the design and implementation of Ka band broadband hybrid integrated image rejection mixer with a fourth harmonic mixer as unit mixer. Detailed design and analysis have been carried out. The mixer was fabricated by hybrid microwave integrated circuit (HMIC) process based on the thin film ceramic substrate which can reduce the cost compared to monolithic microwave integrated circuit (MMIC). The measured results showed conversion loss less than 11.2 dB and image rejection ratio (IRR) more than 20 dB in 4 GHz RF bandwidth. It can also play the role of up-converter from the test data.     

A simple image-reject mixer based on two parallel phase modulators

A simple photonic microwave image-reject mixer (IRM) using two parallel phase modulators is proposed. First, a photonic microwave mixer with phase shift ability is achieved using two parallel phase modulators (PMs), an optical bandpass filter, three polarization controllers, three polarization beam splitters and two balanced photodetectors. At the output of the mixer, two frequency downconverted signals with tunable frequency difference can be obtained. By adjusting the phase difference as 90° and utilizing an electrical 90° hybrid, the useless components can be eliminated, and the image reject operation is realized. The key advantage of the proposed scheme is the usage of PM, which avoid the DC bias shifting problem and make the system simple and stable. A simulation is performed to verify the proposed scheme, a relative ??90° or 90° phase shift can be obtained between the two output ports of the photonic microwave mixer, at the output of the IRM, 60 dB image-reject ratio is obtained.     

Operational Features of a Millimeter-Wave Balanced Mixer with a Broadband Intermediate-Frequency Output

We consider operational and structural features of a millimeter-wave balanced mixer with a broadband intermediate-frequency (IF) output. In this case, the heterodyne frequency is in the close vicinity of the IF band. The problem is reduced to an increase in isolation in the heterodyne-IF circuit along with the decrease in the mixer conversion loss in the broad IF band. As a result, we realized the mixer design with the following parameters: mixer input band 26-40 GHz, IF output band 0-18 GHz, conversion loss 6-8 dB, and heterodyne-IF isolation is 10-20 dB. The mixer circuit based on a combination of waveguide-slotted, coplanar, and microstrip transmission lines is studied.     

Polarization-insensitive all-optical wavelength conversion of 320 Gb/s RZ-DQPSK signals using a Ti:PPLN waveguide

Polarization-insensitive wavelength conversion of a single channel 320 Gb/s RZ-DQPSK data signal using a Ti:PPLN waveguide in a bi-directional loop configuration with less than 0.5 dB polarization sensitivity is reported. The conversion efficiency with polarization scrambling of the signal was ?21 dB, which includes 9.2 dB of passive losses in the whole Ti:PPLN subsystem. In BER measurements error-free operation with 2 dB OSNR penalty for the converted signal was achieved. Theoretical and experimental investigations of the temporal shape and chirp of the converted data pulses show only very little broadening and chirping, indicating the potential for wavelength conversion of even much higher data rates.     

Millimeter wave generation through frequency 12-tupling using DP-polarization modulators

The polarization modulators are being utilized for the millimeter wave (MM-Wave) generation because of their bias drift free operation and high extinction ratio. In this work, an optical millimeter wave generation through frequency 12 tupling using dual parallel polarization modulator (DP-PolM) is demonstrated. By setting RF drive voltage and proper polarization angle of the DP-PolM, the frequency 12-tupled optical millimeter is generated with an optical sideband suppression ratio (OSSR) of 37.76 dB and radio frequency sideband suppression ratio (RFSSR) of 31.67 dB. A good agreement between simulation and theoretical approach is achieved. Further, impact of non ideal parameters on the OSSR, RFSSR and BER are also analysed and presented.     

An ultra-broadband and highly-efficient tunable terahertz polarization converter based on composite metamaterial

A near perfect, ultra-broadband and highly-efficient terahertz reflective polarization converter based on multilayer metamaterial is proposed in this paper. The hybrid metamaterial unit structure consists of a split-ring metal pattern and a metal sheet separated by a dielectric resonator spacer. The polarization conversion ratio (PCR) is above 90% from 2.06 to 4.26 THz, with an optimal range between 2.98 and 4.16 THz where the efficiency is above 98% for normal incidence. It also shows excellent performance for oblique incidences. Moreover, the working band and the optimized frequency range for the polarization conversion can be manipulated by changing the open angle between the metallic arcs and the substrate thickness, respectively. Based on this design, two types of hybrid metamaterial converters are also investigated to swith off polarization conversion altogether or modify the polarization conversion bandwidth. A polarization converter with temperature controlled PCR is realized by adding a vanadium oxide (VO₂) mask on the designed structure. In addition, by integrating photoconductive silicon islands between the split-ring and metal bar a dual-band polarization converter can be realized. Combining with a polarizer, this window can act as an active THz filter.     

A 119 GHz planar Schottky diode mixer for a space application

A planar single-ended GaAs Schottky diode mixer has been designed, built, and tested at 119 GHz. The mixer front end includes also a waveguide filter for image rejection, and a temperature compensated ring filter. Measurements at room temperature showed a conversion loss of 7 dB and a noise temperature of 900 K (SSB). At 100 K the measured noise temperature of the mixer was 500 K (SSB).     

基于十字变形结构的高效超宽带线性极化转换超表面

提出了一种基于十字变形结构超表面的极化转换器,在反射模式下获得了高效超宽带的交叉极化反射.在8.4到20.7GHz频段内交叉极化反射率大于-0.2dB,而共极化反射率小于-12dB,在谐振频率点处交叉极化反射率大于-0.03dB,而共极化反射率达到-60dB,即在谐振点处几乎可实现完全的交叉极化转换;相对带宽达84.5%,交叉极化的平均转换效率为96.7%;此外,利用电路板刻蚀制备了此极化转换器样品,实验测试其交叉极化反射率在工作频段内大于-1dB,而共极化反射率小于-10dB,实验结果与模拟结果吻合,验证了此超表面可以在超宽的频带内实现线极化电磁波的交叉极化转换.本文设计的超宽带极化转换超表面具有转换效率高和几何结构简单的优点,可被扩展到太赫兹甚至是可见光频段.     

Frequency modulated and polarization maintaining fiber laser with narrow linewidth

A novel configuration of fiber laser with frequency modulation is presented. Frequency modulation, stable polarization state and narrow linewidth are realized by using the waveguide phase modulator, polarization maintaining devices and saturable absorber. It is shown that the laser output reaches 23 mW, linewidth is less than 1 kHz, polarization extinction ratio is higher than 20 dB and maximum value of frequency deviation can reach 7.5 MHz.     

基于SPGD算法的非保偏-保偏光自适应偏振转换

报道了一种基于随机并行梯度下降(SPGD)算法的高消光比非保偏-保偏光自适应偏振转换系统。该系统利用偏振控制器对非保偏光的偏振分量进行直接控制,通过SPGD算法对输出的偏振消光比进行优化,最终实现了自适应的非保偏-保偏光的偏振转换。理论上,结合SPGD算法和偏振控制器的原理,对系统进行分析,建立了非保偏-保偏光自适应偏振转换的数学模型。实验上,利用该系统实现了非保偏到保偏光的转换,获得了14.1dB的线偏振光输出;并利用该系统将任意方向(0~360°)偏振态的线偏振光转换为期望偏振态的高消光比线偏光,其输出线偏光的平均消光比约为12dB。     

Switchable microwave photonic filter using a phase modulator and a silicon-on-insulator micro-ring resonator

A switchable microwave photonic filter(MPF) using a phase modulator(PM) and a silicon-on-insulator microring resonator(MRR) is proposed and demonstrated. By adjusting the polarization controller between the PM and the MRR, the filtering function of the MPF can be switched between a band-stop filter and a band-pass filter. In a proof-of-concept experiment, an MPF with a rejection ratio of 30 dB(or 15 dB) for the band-stop(or band-pass) response and a frequency tuning range from 9.6 to 20.5 GHz is achieved.     

A linear-to-circular polarization converter based on I-shaped circular frequency selective surfaces

In this paper, a linear-to-circular polarization converter using a three-layer frequency selective surface based on Ishaped circular structure resonant is presented and investigated. Numerical simulations exhibit that when the normal ypolarized waves impinge on this device propagating towards +z direction, the two orthogonal components of the transmitted waves have a 90° phase difference as well as the nearly equal amplitudes at the resonant frequency of 7.04 GHz, which means that the left-hand circular polarization is realized in transmission. For validating the proposed design, a prototype which consists of 25 × 25 elements has been designed, manufactured and measured. The measured results are in good agreement with the simulated ones, showing that the polarization conversion transmission is over-3 dB in the frequency range of 5.22–8.08 GHz and the axial ratio is below 3 dB from 5.86 GHz to 7.34 GHz.     

Reconfigurable photonic generation of microwave hybrid frequency/phase shift keying signals

A photonic approach for the generation of microwave hybrid frequency/phase shift keying (FSK/PSK) signal based on an integrated polarization division multiplexing dual-parallel Mach–Zehnder modulator (PDM-DPMZM) is proposed and demonstrated. In the scheme, the polarization modulator is employed to modulate the linearly polarized lightwave to generate an optical polarization-shift keying (PolSK) signal. Then the PolSK signal is sent to the PDM-DPMZM via a polarization controller to generate optical PSK signal. After photo-detection, a microwave hybrid FSK/PSK signal can be obtained. Simulations are conducted to verify the proposed scheme. As bit rate is set to 1 Gbit/s, a hybrid FSK/PSK signal with frequency of 10/15 GHz and phase shift of\(\pi\)is successfully demonstrated. Hybrid signals with 2-Git/s frequency shift and 1-Git/s phase shift are also implemented. The compression ratio of the generated signal is 25.5 and the main-to-sidelobe ratio is 11.2 dB. The generations of ASK, PSK and FSK signals are discussed, and the impact of the polarization extinction ratio is also analyzed.     

A flexible wideband bandpass terahertz filter using multi-layer metamaterials

We make a flexible wideband bandpass filter at terahertz (THz) frequencies using multi-layer metamaterials. A very flat response in the passband can be obtained since the Fabry–Perot reflection inside the rigid substrate is eliminated. The center frequency is about 0.89 THz with a 3 dB bandwidth of 0.69 THz for normal incidence. The sharp band-edge transitions are 53 and 70 dB/THz to the rejection bands, respectively. The measured average insertion loss is 1.4 dB with a ripple of 0.8 dB. Furthermore, the transmission feature is insensitive to the polarization of incident wave due to the symmetric structure of the unit cell of the metamaterials. Also, it has a small change as the increase of the curvature of the flexible substrate. This result manifests that the multi-layer metamaterials can provide an effective way to design wideband THz devices.     

一种高功率折线栅极化转换天线罩的设计

设计了一种用于高功率径向线螺旋阵列天线的极化转换天线罩。利用三层介质层包夹双层金属折线,形成密封的埋入式折线栅结构。在实现圆极化与线极化相互转换的同时,又避免金属与空气接触,可以提高功率容量。分析了埋入式折线栅单元各参数的影响,并优化单元参数,以此构建埋入式折线栅极化转换天线罩并加载至X波段高功率径向线螺旋阵列天线,分析了天线的基本性能以及功率容量。仿真结果显示:天线匹配良好,增益和波束宽度变化很小,中心频率轴比由1.16 dB变为40 dB,圆极化波转换为线极化波效果良好;经初步分析,极化转换天线罩的功率容量为121 MW,实现了极化转换天线罩的高功率应用。     

Ultracompact and silicon-on-insulator-compatible polarization splitter based on asymmetric plasmonic–dielectric coupling

An ultracompact and silicon-on-insulator-compatible polarization splitter (PS) is proposed by utilizing asymmetric directional coupling between a hybrid plasmonic waveguide and a strip dielectric waveguide. Owing to the plasmon-assisted asymmetry, birefringence is highly enhanced. Polarization splitting can be realized by strong coupling of one polarization while the other polarization is phase-mismatched. As an example, a PS based on strong TM coupling is demonstrated at the wavelength of 1.55 μm with a coupling length of 4.13 μm. Extinction ratios are 20.9 and 16.4 dB for TM and TE polarizations, respectively. The device is also broadband and fabrication-tolerant.     

Tunable microwave photonic notch filter using a dual-wavelength fiber laser with phase modulation

A novel tunable microwave photonic notch filter using a phase-modulated dual-wavelength fiber laser is presented. A stable dual-wavelength erbium-doped fiber laser with a linear cavity is formed by a polarization-maintaining uniform fiber Bragg grating (PM-FBG) and a polarization maintaining linearly chirped fiber Bragg grating (PM-LCFBG), both of which were fabricated on a high-birefringence (Hi-Bi) fiber. It is found that a stable room-temperature dual-wavelength operation can be achieved due to the presence of two reflection peaks arising from the orthogonal states of polarization (SOP) of the PM-FBG. Experimental results show stable dual-wavelength lasing operation with a wavelength separation of ∼0.36 nm and a large optical signal-to-noise ratio (OSNR) of over 40 dB under room temperature. The dual-wavelength fiber laser is combined with a phase modulator and a segment of single-mode fiber (SMF) as a dispersive device to form a tunable microwave photonic notch filter. By stretching the PM-FBG to tune the wavelength separation of the dual-wavelength fiber laser, a tunable microwave photonic notch filter with various free spectral ranges (FSRs) and a rejection ratio greater than 35 dB was developed.     

基于半导体光放大器交叉偏振调制效应实现正、反相波长变换

利用琼斯矩阵，对基于半导体光放大器中的交叉偏振调制效应实现全光波长变换进行了理论分析.结果表明，利用这种机制可以实现同相与反相波长变换.在实验上同时实现了10Gb/s归零信号的正相与反相波长变换，输出消光比分别达到了6.9 dB和8.1 dB.