一种新型可调谐光子晶体滤波器的理论研究

建立了可调谐光子晶体滤波器的设计标准,作为设计的依据.通过数值计算和理论分析,得出了一维掺杂光子晶体的缺陷模随杂质光学厚度L和光子晶体折射率n2的变化特征.设计出的可调谐一维光子晶体滤波器在理论上能很好地满足设计标准,滤波通道的半高宽(FWHM)可调范围在1～4 nm间,波长λ可调范围达300 nm,透射率峰值大于0.95.     

Widely (132 nm) wavelength tunable laser using a semiconductor optical amplifier and an acousto-optic tunable filter

A widely wavelength tunable laser combining a semiconductor optical amplifier, an acousto-optic tunable filter and a Fabry-Perot etalon has been developed. It exhibited good characteristics over a 132 nm (1480-1612 nm) tuning range.     

New Functional Capabilities of Microwave Interferometry When Using Metastructure as a Tunable Beam Splitter

Journal of Communications Technology and Electronics - It is experimentally shown that the microwave metainterferometer with a metastructure (metasurface or metaatom) as a tunable beam splitter...     

Rapidly tunable narrowband wavelength filter usingLiNbO3 unbalanced Mach-Zehnder interferometers

We demonstrate a rapidly tunable narrowband wavelength filter using unbalanced Mach-Zehnder interferometers in lithium niobate. It is designed to switch among eight channels spaced 50 GHz apart in optical frequency (approximately 0.4 nm in wavelength) in less than 50 ns. The insertion loss is 19 dB and crosstalk is less than -22 dB. The filter consists of a cascade of three electrooptically tunable unbalanced Mach-Zehnders and a feedback circuit to keep the filter centered on the desired wavelength     

CMOS linear programmable transconductor suitable for adjustable Gm-C filters

A novel CMOS linear programmable transconductor is presented. It is based on a telescopic cascode operational transconductance amplifier with source degeneration implemented by means of highly linear tunable active resistors. The transconductor has been designed in a 0.5 mum CMOS technology featuring a third-order intermodulation (IM3) of -54.8 dB at 10 MHz for a 1 V_pp output voltage. Its feasibility for Gm-C filter design has been experimentally validated with a 1 MHz tunable third-order Chebyshev lowpass filter suitable for Bluetooth applications.     

Electrooptic narrow linewidth wavelength tuning and intensity modulation of an erbium fiber ring laser

We report an electrically tunable fiber laser featuring a 50-channel wavelength switching capability with a 0.2 nm linewidth and -20 dB crosstalk. The laser consists of an Er-doped fiber resonator and an electro-optic TE-TM convertor used as a wavelength tunable filter. It allows wavelength tuning over a spectral range of 10 nm with a tuning rate of 0.05 nm/V and a linewidth of 0.06 nm.     

Tunable Infrared Microspectrometer Based on Bragg Grating

This paper presents a tunable, microspectrometer, based upon a Bragg diffraction grating structure, capable of operating in the infrared region of the optical spectrum, nominally 1-10 mum. A 10% tunability and 45% absorptivity is reported for a 2.75-mum free space wavelength microspectrometer. It is shown that by changing the position of a reflecting plane below the Bragg grating, there is a change in the absorption wavelength and absorptivity, thereby realizing a tunable spectrometer. The power absorbed is investigated as a function of reflector position using the finite difference time domain method.     

基于GaAs变容二极管的电调滤波器芯片设计

介绍基于GaAs变容二极管工艺的电调滤波器芯片的研究与设计,包括变容材料制备、二极管模型建立以及电路设计。设计数款电调滤波器,工作频段范围覆盖1~19 GHz。测试结果显示,电调滤波器具有超过一个倍频程的调谐范围,器件击穿电压大于+30 V。本文选取中心频率为2~5 GHz可调的一款电调滤波器进行详细介绍,控制电压范围为0~15 V,插入损耗在10 dB左右,输入和输出驻波(电压驻波比)均优于1.8。设计的系列化电调滤波器具有一致性高、小型化、低成本和免调试等优势,拥有良好的应用前景。     

双光纤光栅法-珀腔可调谐窄线宽激光器

基于游标原理,利用一对自由谱宽(FSR)略有不同的光纤布喇格光栅法布里-珀罗腔(FBG-FP)作为模式选择器件,设计了一种新颖的环形腔光纤激光器。从理论和实验上研究了该激光器的特性。通过对可调谐FBG-FP应力调谐,在1552.240～1552.912 nm范围内,以96 pm为平均间距,获得了8个由固定FBG-FP的透射谱所确定的窄线宽稳定激光输出。8个输出波长的平均功率为-17.66 dBm,波动在0.7 dB范围内。当泵浦光的功率为95 mW的时候,输出信号的信噪比均大于50 dB。实验上每隔1 min用光谱分析仪(OSA)对输出光波长自动扫描,记录的输出光波长漂移在数皮米范围内,且功率的波动小于0.1 dB。这种可调谐的窄线宽光纤激光器在光纤通信和光纤传感方面有潜在的应用价值。     

频率和幅度双可调铁氧体LTCC衰减器

电路小型化需要多频段可调元器件,基于CPW(共面波导)结构采用最新的铁氧体LTCC(低温共烧陶瓷)技术,内埋若干偏置线圈以产生内部偏置磁场,调节线圈内电流大小以控制偏置磁场大小,从而控制衰减器的工作频率,同时,控制通电线圈的个数以改变衰减器的衰减幅度,进而实现频率和衰减幅度双可调的衰减器。首先介绍了基于铁氧体材料的衰减器基本原理,然后展示了基于铁氧体LTCC 技术的无内置线圈衰减器的设计、制作和测量,在外加偏置磁场的条件下,验证了铁氧体LTCC 衰减器的理论可行性,经实测,该衰减器可以在4～9 GHz之间实现频率可调以及相应的衰减幅度可调。随后提出了有内置线圈的铁氧体LTCC 衰减器模型,并展示了线圈静态磁场、衰减器频率可调和幅度可调的仿真结果。最后制作了该衰减器并完成了实测,在铁氧体LTCC特有内部衰减场上实现了频率和幅度双可调衰减器,从而给出了可调衰减器的新思路。     

A 0.13-μ m CMOS Phase Shifter Using Tunable Positive/Negative Refractive Index Transmission Lines

This letter presents a tunable positive/negative refractive index transmission line (TL) phase shifter utilizing active circuits. It comprises a microstrip TL loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) to synthesize a tunable inductor. This implementation increases the phase tuning range and maintains the input and output matching of the phase shifter across the entire phase tuning range, while eliminating the need for bulky passive inductors. The phase shifter is capable of providing both positive and negative phase shifts. The MMIC tunable inductors are fabricated in a 0.13-mum CMOS process and operate from a 1.5-V supply. The phase shifter achieves a phase of -40deg to +34deg at 2.5GHz from a single stage with less than -19dB return loss, and better than 1.1-dB insertion loss at 2.5 GHz. The phase shifter has a 1-GHz bandwidth over which the return loss remains better than 12.1dB     

A tunable far infrared laser

A continuously tunable far infrared (FIR) laser has been demonstrated; experimental results are presented. A high-pressure (10-12 atm) continuously tunable CO2TE laser is used to pump Raman transitions in CH3F; the generation of continuously tunable radiation in the250-300 mum wavelength range is reported. Accurate frequency and bandwidth measurements have been made and the FIR bandwidth in superradiant emission isapprox4-5GHz. Consequently, the generation of frequency tunable, subnanosecond pulses in the FIR appears feasible. The generation of tunable laser radiation from 150 to 1000 μm by stimulated Raman scattering should be possible using higher pump intensity and/or other gases.     

一种新的Lyot型双折射调谐滤光片

石英晶体波片的延迟量对入射倾角有很大的敏感性,利用波片的这一特性,从普通的Lyot型双折射滤光片的基本原理出发,设计了一种新的Loyt型双折射调谐滤光片.调谐的方法是使石英波片绕平行于光轴的轴向转动.理论和实验证明这一设计有较好的可调性,可调范围比较宽.比普通的加入λ/4波片和λ/2波片的Lyot型双折射调谐滤光片简化了结构、降低了成本.     

Octave-tunable miniature RF resonators

The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9dB for a 25MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6GHz, and a tuning speed of 1GHz/ms.     

Novel kind of lyot birefringent tunable filters

The Lyot filter is a monocolour birefringent filterwhichis invented by the French physicist Lyot for theresearches of astronomy,especiallyfor observingthe so-lar corona.Becausethe birefringent filter can be designedof the special optical characters such a…     

LC电调带通滤波器的设计

本文采用桥接网络法设计了一个LC电调带通滤波器,1dB通带连续可调范围为：110～125MHz至110～155MHz、体积为25mm×13mm×7mm。对桥接网络法的椭圆类型滤波器做了深一层研究,找到了提高其矩形系数及带外抑制的改进方法。     

Robust highly linear high-frequency CMOS OTA with IM3 below - 70 dB at 26 MHz

An enhanced configuration for a linearized MOS operational transconductance amplifier (OTA) is proposed. The proposed fully differential OTA circuit is based on resistive source degeneration and an improved adaptive biasing technique. It is robust to process variation, which has not been fully shown in previously reported linearization techniques. Detailed harmonic distortion analysis demonstrating the robustness of the proposed OTA is introduced. The transconductance gain is tunable from 160 to 340 /spl mu/S with a third-order intermodulation (IM3) below -70 dB at 26 MHz. As an application, a 26-MHz second-order low-pass filter fabricated in TSMC 0.35-/spl mu/m CMOS technology with a power supply of 3.3 V is presented. The measured IM3 with an input voltage of 1.4 Vpp is below - 65 dB for the entire filter pass-band, and the input referred noise density is 156nV//spl radic/Hz. The cutoff frequency of the filter is tunable in the range of 13-26 MHz. Theoretical and experimental results are in good agreement.     

A widely tunable erbium-doped fiber laser pumped at 532 nm

A tunable erbium-doped fiber laser with a very wide continuous-tuning range (1522-1567 nm) is discussed. The wide tuning range was achieved using an aluminum/erbium-doped fiber; the aluminum codoping is known to broaden the gain spectrum substantially. The tunable fiber laser has a ring laser configuration utilizing an inline tunable etalon as the tuning element. Continuous tuning over 45 nm in the spectral range of 1522-1567 nm was achieved with 80 nW of pumping at 532 nm, using the second harmonic of a Nd:YAG laser as the pump source     

Design and Analysis of Frequency-Tunable Amplifiers using Varactor Diode Topologies

The design of frequency-tunable amplifiers is investigated and the trade-off between linearity, efficiency and tunability is revealed. Several tunable amplifiers using various varactor diode topologies as tunable devices are designed by using load-pull techniques and their performances are compared. The amplifier using anti-series distortion-free varactor stack topology achieves 38% power added efficiency and it may be tuned from 1.74 to 2.36 GHz (about 35% tunable range). The amplifier using anti-series/anti-parallel topology is tunable from 1.74 to 2.14 GHz (about 23% tunable range) and provides 42% power added efficiency. It is demonstrated that tunable amplifiers using distortion-free varactor stack topologies provide better power added efficiency than the tunable amplifiers using reverse biased varactor diodes and their linearity is similar to that of a conventional amplifier. These amplifiers may facilitate the realization of frequency agile radio frequency transceiver front-ends and may replace several parallel connected amplifiers used in conventional multimode radios.     

An adaptive wavelength tunable optical filter employing anangle-tuned interference filter and an intelligent digital controller

This paper describes an adaptive wavelength tunable optical filter, which is composed of an angle-tuned interference optical filter and an intelligent digital controller. The new angle-tuned interference filter consists of a dielectric interference optical filter and a piezoelectric angle-tuning mechanism. It achieves quick wavelength switching within 2.5 ms in a 30 nm tuning range and a sufficiently low crosstalk less than -30 dB. The intelligent digital controller has two functions: wavelength tracking and wavelength channel selection. Combining these technologies, we have developed a practical low-cost tunable filter suitable for a post-optical-amplifier filter in a high-sensitivity detection system and a channel selector in a WDM system that requires 10-100 ms channel selection time. With a wavelength tracking operation, we have confirmed -35 dBm high-sensitivity detection in 20 nm wavelength range in a 10 Gb/s system. We have also confirmed a wavelength channel selection operation within 18 ms in a three-channel wavelength division multiplexed (WDM) system whose channel spacing is 4.4 nm