Microwave Phase Shifter Research Articles

Influence of High-Frequency Characteristic of a Cavity on the Phase Shift in the Relativistic Klystron Amplifier

The influences of the eigenfrequency and the intrinsic quality factor of a cavity on the phase shift in the relativistic klystron amplifier (RKA) are investigated. An analytical expression is derived to describe the phase of the gap voltage in a cavity. The theoretical and simulation results indicate that the eigenfrequency of the buncher cavity can significantly affect the phase shift of the output microwave in the RKA. In contrast, the influences of the eigenfrequency and the intrinsic quality factor of the output cavity on the phase shift of the RKA are small. The analytical expression can effectively estimate the phase difference among different RKAs resulting from the machining and assemblage inconformity in the experiment. It is suggested that the differences among the eigenfrequencies of the buncher cavities should be managed in 0.1% of the operation frequency to achieve phase locking among different RKAs.

Simple Method for Phosphorus Diffusion on <100> Oriented P-Type Silicon Using New Phosphorus Gel as Dopant

In this work, we try to make a p-type monocristalline silicon pn junction using an easier doping method. We combined spin-coating thin film deposition method and solid doping technique. This technique can be considered as variety of the SOD method. In this study, phosphorous-based gel compounds was prepared and deposited by spin coating. Heat treatment would thus, after deposition of thin layer, diffuse phosphorus atoms into the substrate to obtain a pn diode. Study by Secondary Ions Mass Spectrometry (SIMS) showed a surface phosphorus concentration of 10 20 at/cm 3 incorporated within the silicon substrate to a depth of 300 nm. The microwave phase-shift (µW-PS) technique is used to determine the bulk lifetime ( τ b) of minority carriers. In this technique, the phase-shift between a microwave beam (10 GHz) and a sine-modulated infrared excitation is related to τb and to the surface recombination velocity (S) (Palais, Clerc, Arcari, Stemmer & Martinuzzi, 2003). The lifetime τb mean values vary from 7 µs for a p-type Silicon to 97 µs for phosphorus-diffused silicon. The surface recombination velocity S varies from around 500 to 1000 cm.s -1 .

Influence of weak anchoring on the microwave phase modulation of liquid crystals

The microwave modulation induced by liquid crystals is determined by the orientation of liquid crystal molecules under an external applied voltage. The anchoring of substrate has an important effect on the liquid crystal orientation, which results in the change of microwave modulation. In this paper, the microwave modulation property of 90 twisted nematic liquid crystals with weak anchoring without chiral dopant is studied. Based on the elastic theory of liquid crystals and the variational theory, the equations of equilibrium state and the boundary condition are given, and the variations of phase-shift per unit-length with voltage for different anchoring energy coefficients and pre-tilt angles are also simulated using the finite-difference iterative method. Results are as follows: (1) The influence of pre-tilt angle on microwave phase-shift is related to the applied voltage. When the voltage applied to the liquid crystal cell is from 0.5 to 1.6 V, with increasing pre-tilt angle, the microwave phase-shift per unit-length and the phase-shift difference relative to the strong anchoring 90 twisted nematic liquid crystal with pre-tilt angle 0 will all increase, and the applied voltage for the maximum phase-shift difference decreases. When the applied voltages are from 1.6 to 3.0 V, the microwave phase-shift per unit-length and the phase-shift difference all decrease with increasing pre-tilt angle. When the applied voltages are near 1.6 V or larger than 3.0 V, the phase-shift per unit-length has little change. (2) The anchoring energy strength has a great influence on microwave phase-shift. As the anchoring strength decreases, the microwave phase shift per unit-length and the phase-shift difference will increase, also the tunable range of microwave phase-shift increases more and more obviously. This research provides a theoretical foundation for the design of the liquid crystal modulator.

Monolithic Microwave Nonlinear Phase Shifter

A microstrip-based microwave phase shifter that includes a thin Fe film as the active element was designed and fabricated. The device is a monolithic microwave structure that is lightweight and can be integrated on a semiconductor chip. At a fixed frequency, a large change in the phase, , was observed as the power was varied. For 1GHz below the resonance frequency, the maximum power-dependent phase shift is δφ = 55°, and for 1GHz above the resonance frequency the maximum phase shift is δφ = 74°. The experimental results show three different regimes: 1) a linear regime for powers up to 6.3 mW, 2) a stable nonlinear regime for power levels from 6.3 mW to about 1W, and above this, 3) an unstable nonlinear regime. The second regime can be used for microwave signal processing.

Performance improvement of S-band phase shifter using Al, Mn and Gd doped Y3Fe5O12 and sintering optimization

The searching for Y3Fe5O12 (YIG) ferrite base material is a difficult challenge for microwave phase shifter. Although YIG ferrite is promising for its good microwave characteristics, the adjustment of its corresponding magnetic properties for applied frequency is always a tough challenge. In this work, a study was made to evaluate the impacts of stoichiometry and sintering temperature on hysteresis properties of Mn, Al and Gd substituted YIG ferrites. The Mn, Al substituted YIG ferrite, (Y3)(MnxAl0.83−xFe4.17)O12 showed its best properties for application in 2–4GHz frequency range (i.e. S-band) latching phase shifter at x=0.13. Magnetic properties were further improved by sintering optimization. The increasing sintering temperature increases saturation magnetization (4πMs), remanence (Br) and squareness ratio (SQR), while decreasing the coercivity (Hc). To further investigate the impact to sintering process, Gd substituted YIG ferrites are also discussed. (Y3−yGdy)(Mn0.13Al0.7−0.5yFe4.17)O12 with y=0.6 demonstrated its best magnetic properties at 1450°C sintering. Although the 4πMs, Br and SQR are comparable to that of previous results, its Hc cannot meet the requirement. (Y3)(MnxAl0.83−xFe4.17)O12 ferrites with x=0.13 sintered at 1430°C shows the optimum magnetic properties: 4πMs=675G, Br=575G, Hc=0.45Oe, SQR=0.86. Good ferromagnetic resonance (FMR) linewidth (i.e. ΔH) were also realized as 38.6Oe at 3.2GHz. Base on above results, we reveal Mn, Al substituted YIG ferrite is a good candidate for practical latch phase shifter applications at S-band.

Experimental characterization and modeling of the improved low frequency response of a current modulated bulk RSOA slow light based microwave phase shifter

The enhancement of the low frequency gain response of a microwave phase shifter based on slow light in a TO-can packaged bulk reflective semiconductor optical amplifier, by using forced coherent population oscillations achieved by simultaneously modulating the input optical power and bias current, is experimentally demonstrated. The beat-signal gain improvement ranges from 35 to 0dB over a frequency range of 0.5–3.5GHz, thereby improving the noise performance of the phase shifter. Tunable phase shifts of up to 55° are possible over this frequency range. Simulations that show good agreement with experiment, based on a wideband dynamic model that includes spontaneous emission and band structure based calculations of the amplifier active region material, are also presented.

Magnonic Bandgap Control in Coupled Magnonic Crystals

The periodic structure in the form of two coupled magnonic crystals (MCs) was considered for the first time. It was shown that the variation of coupling allows to control effectively the characteristics of the bandgaps in the spectrum of magnetostatic spin waves. Main features of formation of the bandgaps were investigated in the basis of theoretical and experimental results. The comparison with a periodic structure in the form of a single MC was provided. The possibility of formation of two frequency bandgaps and shift of the frequency bandgaps depending on coupling was demonstrated in the frequency region of the first Bragg resonance. It was shown that the control of bandgaps in such structure gives additional opportunities to create microwave filters and phase shifters with desired characteristics.

Nonlinear microwave phase shifter on electromagnetic-spin waves

Nonlinear microwave phase shifter based on a multiferroic structure consisting of layers of iron-yttrium garnet and barium—strontium titanate is studied experimentally. The structure is a waveguide for nonlinear electromagnetic-spin waves. The triple control over phase shift of electromagnetic-spin waves (namely, by varying the power of the input microwave signal, the magnetic bias field of the structure, and electric displacement field) is demonstrated.

Photonic generation of triangular pulses based on nonlinear polarization rotation in a highly nonlinear fiber.

We propose a novel method to generate triangular pulses based on the nonlinear polarization rotation (NPR) effect in a highly nonlinear fiber. A continuous wave probe beam is polarization-rotated by an intensity-modulated control beam via the NPR effect. A polarization-division-multiplexing emulator is exploited to split the probe beam into two orthogonally polarized states with imbalanced time delay. After detection by a photodetector, a 90° microwave phase shifter is used to compensate the phases of the fundamental and the third-order harmonic components in order to generate triangular pulses. Triangular pulses at 5 and 6 GHz with full duty cycles are experimentally generated. The root mean square errors between the generated and the simulated waveforms are 3.6e-4 and 1e-4 for triangular pulses at 5 and 6 GHz, respectively.

Magnonic crystals-based tunable microwave phase shifters

Tunable microwave phase shifters using magnetostatic backward volume waves in yttrium iron garnet/gadolinium gallium garnet thin film-based one-dimensional (1-D) and two-dimensional (2-D) magnonic crystals (MCs) are reported in this paper. Large differential phase shifts with small insertion loss variations were achieved in the passbands neighboring the bandgaps by tuning of the bias magnetic field. Large phase tuning rates up to 13.48 °/(Oe cm) and 25.9 °/(Oe cm) together with small insertion loss variations of 2.08 dB/cm and 0.97 dB/cm were demonstrated in the 1-D and 2-D MCs, respectively. An excellent agreement between the measured and the calculated results based on Walker's equation was obtained.

Generation of triangular waveforms based on a microwave photonic filter with negative coefficient.

We report a novel approach to generating full-duty-cycle triangular waveforms based on a microwave photonic filter (MPF) with negative coefficient. It is known that the Fourier series expansion of a triangular waveform has only odd-order harmonics. In this work, the undesired even-order harmonics are suppressed by the MPF that has a periodic transmission response. A triangular waveform at fundamental frequency can be generated by setting the bias of a Mach-Zehnder modulator (MZM) at quadrature point. However, it is found that a broadband 90° microwave phase shifter has to be used after photodetection to adjust the phases of odd-order harmonics. Alternatively, a frequency doubling triangular waveform can be generated by setting the bias of the MZM at maximum or minimum transmission point. This approach is more promising because the broadband microwave phase shifter is no longer required in this case but it is more power consuming. The proposed approach is theoretically analyzed and experimentally verified.

Optically controlled microwave phase shifter based on nonlinear polarization rotation in a highly nonlinear fiber.

This Letter reports an optically controlled microwave phase shifter with an ultra-wideband working bandwidth and a full 360° phase shifting range based on nonlinear polarization rotation (NPR) in a highly nonlinear fiber (HNLF). A continuous wave probe light is modulated by a polarization modulator (PolM) that is driven by a microwave signal to be phase shifted. The optical carrier and the first-order sidebands of the probe light experience different phase shifts due to the NPR induced by the control light in the HNLF. An optical bandpass filter is used to realize single-sideband modulation of the probe light by removing one of the first-order sidebands, as well as to reject the control light. After detecting by a photodetector, the phase of the recovered microwave signal is continuously tunable by adjusting the power of the control light. The proposed approach is theoretically analyzed and experimentally verified. A full 360° tunable phase shift is realized over an ultra-wideband frequency range from 8 to 38 GHz when the power of the control light is tuned from 0 to 570 mW.

Monolithically integrated, ultrahigh-frequency cavity nano-optoelectromechanical system with on-chip germanium waveguide photodetector.

We report the first demonstration of a cavity optoelectromechanical system integrated monolithically with a high-efficiency germanium photodetector on a CMOS-compatible platform. Mechanical resonances are recorded from 0.177 to 2.003GHz with quality factor up to 4810. These monolithically integrated devices have paved the way for a new category of on-chip optoelectronic components that take the advantage of the resonant properties of the mechanical element and enables new applications such as ultracompact microwave oscillators, optomechanical sensors, and phase shifters.

A microwave phase shifter based on a planar ferrite-ferroelectric thin-film structure

Microwave phase shifters employing slot transmission lines based on thin ferroelectric films of barium strontium titanate and thin single-crystalline films of yttrium iron garnet ferrite have been experimentally studied for the first time. The phase shifters admit double electronic control based upon the phenomenon of hybridization of the electromagnetic wave propagating in a slot delay line on the ferroelectric film and the spin wave propagating in the ferrite film. At a bias voltage of 150 V applied to electrodes of the slot lines with 50- and 150-μm-wide slots, the phase shift amounted to 53° and 26°, respectively.

All-thin-film multilayered multiferroic structures with a slot-line for spin-electromagnetic wave devices

Spin-electromagnetic waves propagating in thin-film multilayered multiferroic structures containing a slot transmission line have been investigated both experimentally and theoretically. The thin-film structure was composed of a ferrite film, a ferroelectric film, and a slot-line. It was shown that the spectrum of the spin-electromagnetic wave was formed as a result of hybridization of the spin wave in the ferrite film with the electromagnetic wave in the slot-line and was electrically and magnetically tunable. For the experimental investigations, a microwave phase shifter based on the multiferroic structure has been fabricated. Performance characteristics are presented.

Photonic-assisted microwave phase shifter using a DMZM and an optical bandpass filter

We propose and demonstrate a photonic-assisted wideband 360° microwave phase shifter based on a conventional dual-drive Mach-Zehnder modulator (DMZM) and an optical bandpass filter (OBPF). The two arms of the DMZM are driven by the fundamental microwave signal to be phase shifted and its frequency doubled component, respectively. The OBPF followed after the DMZM is used to remove the optical carrier and the sidebands at either side of the optical carrier. As a result, only two sidebands corresponding to the fundamental microwave signal and its frequency doubled component, respectively, are left. Moreover, the phase shift between the two sidebands can be continuously tunable by adjusting the bias voltage of the DMZM. This phase shift is mapped to the fundamental microwave signal which is recovered by beating the two sidebands in a photodetector (PD). The proposed approach is theoretically analyzed and experimentally verified.

Compact phase shifter based on highly anisotropic liquid crystals for microwave frequency

A compact microwave phase shifter was designed and fabricated using highly anisotropic liquid crystals (LCs). It comprises a thin LC layer between a ground plane and a directly coupled and inverted microstrip line. The proposed folding configuration is beneficial for size reduction. Both simulation and experimental results confirm the compact size devices with reasonably good performance.

New opportunities in microwave electronics with ferromagnetic nanowires

A series of monolithic tunable microwave band-stop filters and phase shifters have been designed, fabricated, and characterized on arrays of ferromagnetic nanowires (FMNWs) constituted of Ni, Co, CoFeB, and NiFe alloy embedded in anodic alumina templates (AAO). The aim of the present investigation is to significantly boost the operating frequency of devices in very low applied magnetic field. The stop-band response can cover from 8 to 40 GHz with an applied magnetic field up to 5 kOe using these materials. In addition, we observed a substantial increase in frequency tunability (>110%) for Ni and NiFe alloy based filter. Frequency bandwidth/linewidth can be tuned with the proper choice of magnetic material, broad band for Co nanowires to narrow band for CoFeB nanowires. The amorphous nature of CoFeB reduces linewidth considerably and hence increases resonance absorption. It is also observed that the frequency linewidth (Δf) decreases with increasing applied magnetic field. The same filter can be used as a tunable phase shifter. For Ni nanowire based phase shifter, a maximum shift of 75°/cm at 4 kOe was observed.

Ultra-wideband microwave photonic phase shifter with a 360° tunable phase shift based on an erbium-ytterbium co-doped linearly chirped FBG

A simple photonic approach to implementing an ultra-wideband microwave phase shifter based on an erbium-ytterbium (Er/Yb) co-doped linearly chirped fiber Bragg grating (LCFBG) is proposed and experimentally demonstrated. The LCFBG is designed to have a constant magnitude response over a reflection band, and a phase response that is linear and nonlinear in two sections in the reflection band. When an optical single-sideband with carrier (OSSB+C) signal is sent to the LCFBG, by locating the optical carrier at the section corresponding to the nonlinear phase response and the sideband at the section corresponding to the linear phase response, a phase shift is introduced to the optical carrier, which is then translated to the microwave signal by beating the optical carrier and the sideband at a photodetector. The tuning of the phase shift is realized by optically pumping the Er/Yb co-doped LCFBG by a 980-nm laser diode. The proposed ultra-wideband microwave photonic phase shifter is experimentally demonstrated. A phase shifter with a full 360° phase shift with a bandwidth from 10 to 40 GHz is experimentally demonstrated.

Nonlinear multiferroic phase shifters for microwave frequencies

A nonlinear microwave phase shifter based on a planar multiferroic composite has been studied. The multiferroic structure is fabricated in the form of a bilayer consisting of yttrium iron garnet and barium strontium titanate. The principle of operation of the device is based on the linear and nonlinear control of the phase shift of the hybrid spin-electromagnetic waves propagating in the bilayer. The linear control is realized with magnetic and electric fields. The nonlinear control is provided by the input power of microwave signal. The device showed a nonlinear phase shift up to 250°, electric field induced phase shift up to 330°, and magnetic field induced phase shift of more than 180°.