80 Gbit/s wavelength conversion using semiconductor optical amplifier and optical bandpass filter

A wavelength converter is presented that is made out of a semiconductor optical amplifier and an optical bandpass filter. Error-free inverted wavelength conversion is demonstrated at a bitrate of 80 Gbit/s. This approach can be exploited at higher bitrates. A clear open eye indicating error-free wavelength conversion at 160 Gbit/s is also presented. This wavelength converter has a simple configuration and allows photonic integration.     

RC active bandpass filter synthesis using a voltage amplifier

An active RC filter employing a voltage amplifier as the active element has been chosen. The root sensitivity of the filter with respect to change in the gain of the amplifier has been calculated and minimized to establish a method of synthesis for achieving stability of center frequency and bandwidth.     

Cyclic and rectangular passband optical bandpass filter using AWG pair

A novel optical bandpass filter is proposed that consists of an arrayed-waveguide grating pair and an optical slit. A 200 GHz cyclic and 40 GHz passband optical filter using the proposed configuration, which is useful for WDM single sideband filtering, is successfully demonstrated.     

Tri-band microstrip bandpass filter using input/output cross coupling

A compact tri-band bandpass filter using input/output cross coupling is proposed. Three passbands can be adjusted by changing the characteristic impedance of the T-shaped structure with a shorted stub. The three passbands are designed to operate at 1.85, 3.5 and 5.2 GHz based on the T-shaped structure. Four transmission zeros are used to realise high selectivity for the passbands. Good agreement can be observed between the measured and simulated results.     

A thermally tunable terahertz bandpass filter with insulator-metal phase transition of VO2 thin film

A terahertz bandpass filter with the sandwich structure consisting of thermally tunable vanadium dioxide （VO2） thin film, silica substrate and subwavelength rectangular Cu hole arrays is designed and theoretically analyzed. The results show that the transmittance of the filter can be actively tuned by controlling the temperature of VO2, the narrow band terahertz （THz） waves with the transmittance from 85.2% to 10.5% can be well selected at the frequency of 1.25 THz when the temperature changes from 50 ℃ to 80 ℃, and the maximum modulation depth of this terahertz bandpass fil- ter can achieve 74.7%.     

Current mode allpass/notch and bandpass filter using single CCII

A current mode second-order allpass notch and bandpass filter using a single CCII, two grounded capacitors and four resistors is proposed. The allpass and notch output current signals, taken out through port z of a CCII and having high output impedance, can be obtained by tuning a resistor in the proposed network. The resonance angular frequency and quality factor of the new network have the advantages of low passive sensitivities and are insensitive to the current tracking error of the nonideal CCII.<>     

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.     

Compact microstrip bandpass filter using both ?/2 and ?/4 resonators

A design procedure for a composite filter having interdigital input and output sections, separated by a ?/2 resonator, is outlined. Results from a prototype filter show improved characteristics by comparison with purely interdigital or parallel coupled filters. The passband is in closer agreement with theoretical predictions than is usual for microstrip interdigital filters.     

Miniaturised microstrip bandpass filter using octagonal hairpin resonators with side-coupled technique

A miniaturised elliptic-function-response bandpass filter using octagonal double-hairpin-shape resonators with side-coupled stubs has been designed and fabricated. Measured results are in good agreement with the electromagnetic simulation results and verify that the central frequency and the passband range of the proposed filter are 968 and 950?990 MHz, respectively. Also, its electric coupling characteristics and field distributions are investigated. The circuit size of the proposed filter occupies only 22.6 X 14.3 mm (=0.13λ_g) X 0.085λ_g).     

圆形开槽贴片微带双模带通滤波器

提出了一种新颖、简单的圆形贴片上刻蚀小方槽的微带双模带通滤波器结构.该滤波器仿真的通带中心频率为5.9 GHz,最大回波损耗优于-31.5 dB,通带内最小插入损耗为- 0.7 dB,3 dB带宽为23.73％.实测和仿真结果相一致.     

Micromachined V-band CMOS bandpass filter with 2 dB insertion loss

A low-insertion-loss V-band CMOS bandpass filter is demonstrated. The proposed filter architecture has the following features: the low-frequency transmission-zero (vz1) and the high-frequency transmission-zero (vz2) can be tuned by the series-feedback capacitor Cs and the parallelfeedback capacitor Cp, respectively. To reduce the substrate loss, the CMOS process compatible backside inductively-coupled-plasma (ICP) deep trench technology is used to selectively remove the silicon underneath the filter. After the ICP etching, this filter achieved insertion loss (1/S21) lower than 3 dB over the frequency range 52.5?76.8 GHz. The minimum insertion loss was 2 dB at 63.5 GHz, the best results reported for a V-band CMOS bandpass filter in the literature.     

A miniaturized net-type microstrip bandpass filter using /spl lambda//8 resonators

A novel miniaturized three-pole net-type bandpass filter using /spl lambda//8 resonators has been proposed. Asymmetric frequency characteristics of this filter exhibit a single transmission zero on the lower side of the passband at finite frequency, which is attributed to multi-path effect. Full-wave simulator IE3D is used to extract the coupling coefficients and external quality factor in order to determine the physical dimensions of this filter. The measured results are in good agreement with the simulated predictions. The overall size of the filter is only about 0.22/spl lambda//sub g/ by 0.2 /spl lambda//sub g/. As a result, the filter has not only a small size but also a wider upper stopband up to 6.5 f/sub 0/.     

Microstrip bandpass filter using one single patch resonator with two transmission zeros

A novel compact and simple microstrip patch bandpass filter structure using only one resonator is presented. This filter has two transmission zeros on both sides of the passband. Without coupling gaps, the new filter can reduce uncertainty in fabrication. Simulated results agree well with measured results.     

Miniaturized dual-band bandpass filter with good frequency selectivity using SIR and DGS

A miniaturized dual-band bandpass filter (BPF) using stepped impedance resonator (SIR) and defected ground structure (DGS) is presented. In order to get two desired passbands, two different transmission paths and source–load cross coupling have been implemented. One path is the SIR, and the other is the DGS. Meanwhile, it is easy to obtain good frequency selectivity by introducing several transmission zeros. The coupling scheme and current distributions are applied to demonstrate the flexible design approach. A dual-band BPF is designed, simulated, and fabricated to demonstrate the performance of the proposed dual-band filter. The measured results show that the fabricated dual-band BPF has two passbands centered at 2.41 and 3.52 GHz with the fractional bandwidth of 5.8 and 7.7%, respectively. The measured insertion loss is about 2 dB and 2.2 dB at the lower and upper passbands. The measured results show good agreement with the simulated ones.     

Compact tri‐wideband bandpass filter with multiple transmission zeros

This paper presents a tri‐wideband bandpass filter (TWB‐BPF) with compact size, high band‐to‐band isolation, and multiple transmission zeros (TZs). The proposed TWB‐BPF is based on a multiple‐mode resonator (MMR), which is interpreted by the method of the even‐ and odd‐mode analysis technique. The MMR can excite 11 resonant modes, where the first two modes comprise the first passband, the next four modes form the second passband, and the last five modes are used to generate the third passband. In addition, 10 TZs are yielded to obtain high band‐to‐band isolation and wide stopband suppression characteristics up to 14.95f_c1 (f_c1 is the center frequency of the first passband). To verify the proposed filter, a TWB‐BPF with 3‐dB fractional bandwidths (FBWs) of 37.4%, 43.5%, and 40.4% is designed, fabricated, and measured.     

Effect of phase shift position on spectral linewidth of the π/2distributed feedback laser diode

The dependence of the spectral linewidth on the phase shift position (PSP) of a phase-shifted distributed-feedback (DFB) laser diode is investigated theoretically, using the coupled wave model. In particular, the analysis is performed to find an optimum PSP so as to minimize the spectral linewidth of the laser diode. This optimum PSP is compared to that obtained by maximizing the stability of the laser oscillation. Since both narrow spectral linewidth and good stability are essential for the light source in coherent optical communications, the analysis revealed the suitability of using phase-shifted DFB laser diodes in coherent transmissions     

Microstrip dual-band bandpass filter with independently tunable passbands using varactor-tuned stub loaded resonators

In this paper, a dualband bandpass filter with independently tunable passband is proposed. Two half-wavelength resonators with shunt stub have been placed side by side, fed with a common input-output microstrip line to achieve the individual tunability without affecting other passband. For tuning resonance frequency, varactor diodes are used at the ends of the half wavelength resonators and also at the end of the shunt stubs. Proper shunt stub length and width are derived numerically in such a way that only one control voltage is required in each passband. Measured results show that lower passband can be tuned in a frequency range from 1.78 to 1.96 GHz, whereas the upper passband varies from 2.27 to 2.39 GHz individually. H shaped DGS is integrated below the input-output feed lines to suppress higher order harmonics up to 21 GHz with more than 19 dB attenuation.     

Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.     

Optimisation of SIW bandpass filter with wide and sharp stopband using space mapping

This work presents a substrate integrated waveguide (SIW) bandpass filter with wide and precipitous stopband, which is different from filters with a direct input/output coupling structure. Higher modes in the SIW cavities are used to generate the finite transmission zeros for improved stopband performance. The design of SIW filters requires full wave electromagnetic simulation and extensive optimisation. If a full wave solver is used for optimisation, the design process is very time consuming. The space mapping (SM) approach has been called upon to alleviate this problem. In this case, the coarse model is optimised using an equivalent circuit model-based representation of the structure for fast computations. On the other hand, the verification of the design is completed with an accurate fine model full wave simulation. A fourth-order filter with a passband of 12.0–12.5 GHz is fabricated on a single layer Rogers RT/Duroid 5880 substrate. The return loss is better than 17.4 dB in the passband and the rejection is more than 40 dB in the stopband. The stopband is from 2 to 11 GHz and 13.5 to 17.3 GHz, demonstrating a wide bandwidth performance.     

Inline optical filter using lifted-off GaAs/AlGaAs multilayer

A new inline optical filter is reported. A GaAs/AlGaAs multilayer interference filter was lifted off its GaAs substrate by selective etching, and was sandwiched between two gradient-index rod lenses. Near-theoretical performance was obtained, with over 20 dB rejection in the stop band and less than 0.5 dB insertion loss at transmission peaks. This type of filter could be extremely useful in wavelength division multiplexed systems.<>