We report a novel approach to generating full-duty-cycle triangular waveforms based on microwave photonic filter (MPF) with negative coefficient. It is known that the Fourier series expansion of waveform has only odd-order harmonics. In this work, undesired even-order harmonics are suppressed by MPF periodic transmission response. A at fundamental frequency can be generated setting bias Mach-Zehnder modulator (MZM) quadrature point. However, it found broadband 90° phase shifter used after...

We demonstrate a novel scheme to generate full-duty-cycle triangular microwave waveforms using an optoelectronic oscillator (OEO). The OEO produces high-quality local signal. Thus, external source, which is usually involved in orthodox approaches obviates the need. A polarization modulator both loop and photonic filter (MPF) structure. To waveform, undesired electrical harmonics are suppressed by MPF. proposed method theoretically analyzed experimentally verified. Triangular at fundamental...

Karst geology creates a complex environment with diverse landforms, blurred boundaries, and multi-factor interactions. This paper presents new drilling pile installation method: drill to set depth, clean the hole, insert prefabricated piles, drive or vibrate them target elevation. It suits tough geological conditions well. Pile foundations bear both axial lateral eccentric loads. To explore prestressed high-strength concrete (PHC) under vertical loads in karst areas, on-site bearing capacity...

We report a new photonic microwave pulse generator using phase-modulator-based Sagnac interferometer (PM-SI) and wavelength-to-time mapping in dispersive element. The key significance of the proposed scheme is that phase generated can be continuously tuned by adjusting bias voltage applied to PM. Thanks wide bandwidth PM, high-speed modulation realized. Moreover, PM-SI polarization independent, which means insensitive state input optical signal, ensuring stable operation system....

We report a new radio-frequency (RF) phase stabilization approach for long-haul optical fiber distribution. The drift of an RF signal induced by fiber-length variations can be canceled out automatically via mixing without using active discrimination and dynamic tracking. A key significance our is that no assistant local oscillator (LO) needed. Consequently, frequency estimation the received signal, as well locking between LO longer required, which simplifies system. proof-of-concept...

A widely tunable single bandpass microwave photonic filter (MPF) based on Brillouin-assisted optical carrier recovery in a highly nonlinear fiber (HNLF) with only one is proposed and experimentally demonstrated. The fundamental principle lies the fact that suppressed of phase modulated signal could be recovered by stimulated Brillouin scattering (SBS) amplification effect. When signals go through an response, upper sidebands suffer from suppression because they fall stopband that. In our...

We propose a novel method to generate triangular pulses based on the nonlinear polarization rotation (NPR) effect in highly fiber. A continuous wave probe beam is polarization-rotated by an intensity-modulated control via NPR effect. polarization-division-multiplexing emulator exploited split into two orthogonally polarized states with imbalanced time delay. After detection photodetector, 90° microwave phase shifter used compensate phases of fundamental and third-order harmonic components...

We propose a new method to improve the accuracy of an optical vector network analyzer (OVNA) based on stimulated Brillouin scattering (SBS) in dispersion-shifted fiber (DSF). Generally, measurement error OVNA mainly derives from beat signals between adjacent sidebands. In this paper, is significantly suppressed using two-step process. For first measurement, both transmission response device-under-test (ODUT) and are recorded. second only obtained by suppressing carrier SBS DSF. The accurate...

We proposed a new approach to generate full-duty-cycle triangular waveforms using sinusoidal radio-frequency (RF) signal based on stimulated Brillouin scattering. In order waveform, the even-order harmonics of RF has be removed. our scheme, we use both pump and Stokes waves manipulate amplitudes phases optical components. this way, fundamental tone its can controlled. The method is theoretically analyzed experimentally verified. For proof-of-concept demonstration, at 8.5, 10.5, 12.5 GHz are...

A microwave photonic filter (MPF) with complex coefficient based on the frequency transparent magnitude response by independent control of and power two stimulated Brillouin scattering (SBS) pumps is proposed experimentally demonstrated. The motivation this paper lies in fact that operation bandwidth previous SBS-based MPFs unavoidably limited shift. In our scheme, coefficients are obtained a broadband phase shifter SBS pumps. pump signals located at same side optical carrier. principle,...

We propose and experimentally verify an approach to generate pulsed microwave signal with continuously tunable phase discrete tuning in frequency based on shifted Lyot optical filter conjunction wavelength-to-time mapping technology. The the discretely spectral spacing is realized by changing state of polarization bidirectionally propagated signals. response tuned over a full free-spectral range (FSR) keeping its shape FSR unchanged simple adjusting bias voltage modulator. proposed could...

In order to study the influence factors of vertical bearing capacity pile foundation under special address condition multi-layer karst cave, finite element model in double-layer area was established by using a commercial general software Ansys, concrete with different rock height, ec-centricity and elastic modulus gradually increasing load studied. The results show that: (1) Under constant external load, maximum displacement increases increase eccentricity; (2) With strength, decreases...

Pile foundations are widely employed in engineering to bolster structures and efficiently transmit loads the underlying soil or rock. However, karst terrains, occurrence of multi-layered stone projections caves can drastically affect bearing capacity stability these pile foundations. In order study influencing factors vertical founda-tion multi-layer cave environment, test foundation was carried out at construction site. The results show that with increase external load eccentricity,...

A novel technique to generate frequency quadrupling microwave signal is proposed and experimentally demonstrated based on a Brillouin-assisted optical notch filter (BAOF). The intensity modulated firstly working at the maximum transmission point suppress first order sidebands. Microwave signals corresponding four times of fundamental tone are successfully generated.

Test model who’s scale is 1:10 was established. According to the actual engineering, through test, laws about settlement of pile-raft foundation, vertical and horizontal soil, pile force, soil force pile-soil stress ratio were studied under natural uniform variable diameter foundation. It can provide theoretical basis for Future research raft