Microwave Photonic Downconverter Research Articles

Simple microwave photonic downconversion channelizer based on multi-wavelength laser sources.

This work presents a simple microwave photonic downconversion channelizer based on multi-wavelength laser sources. The design of two laser diode (LD) arrays enables signal multiplexing and simultaneous multichannel downconversion processing, which provide stable, relatively flat, and strong multi-frequency combs. A proof-of-concept experiment was taken, showing that 14.375-17.75 GHz broadband radio frequency (RF) signals were successfully downconverted to the same intermediate frequency (IF) and were sliced into four subchannels with 875 MHz bandwidth showing excellent image rejection and channel uniformity, which agrees with the simulation results. The spurious free dynamic range (SFDR) of the proposed RF channelizer is 100dBHz2/3, the image rejection is over 28 dB, and the frequency measurement error is less than ±6MHz. Replacing optical filters with electrical filters, the proposed simple optoelectronic hybrid reconfigurable microwave photonic channelizer system acquits stable performance and high maturity and meets the application requirements, behaving with stupendous potential in fields such as radar, satellite communication, electronic warfare, and others.

Wideband Microwave Phase Noise Analyzer Based on All-Optical Microwave Signal Processing

An approach for wideband phase noise measurement of microwave signal sources is proposed based on all-optical microwave signal processing. In the proposed scheme, an optical carrier is sequentially modulated by the signal under test (SUT) in a phase modulator and a dual-polarization modulator to generate two +1st-order sidebands with orthogonal polarizations. A time delay is introduced between two sidebands by a span of low-loss optical fiber. Combined with a polarization controller and a polarizer, photonic microwave downconversion with a desired phase shift and time delay can be realized after photodetection, and the phase noise of the SUT can be calculated thereafter. Since all the microwave signal processing functions in the conventional photonic-delay-line-based phase noise measurement system are implemented in the optical domain, the proposed scheme has a large operational bandwidth and a high measurement sensitivity. In the experimental demonstration, accurate phase noise measurement of SUTs is achieved in a frequency range of 10-35 GHz, and a phase noise floor as low as −132.16 dBc/Hz at 10 kHz is obtained.

Microwave Photonic Mixer Using DP-DDMZM for Next Generation 5G Cellular Systems

ABSTRACT Microwave frequency down-conversion at 4.5 GHz using proposed photonic mixer is analyzed on various aspects in this manuscript. The proposed microwave photonic down-converter employs a Dual-Parallel Dual-Drive Mach–Zehnder Modulator (DP–DDMZM) that makes the system more compact than previously reported photonic mixers. Suppressed carrier modulation technique is used to increase the sideband power, which improves conversion efficiency by 20 dB as compared to dual-series modulator based mixer. To examine the performance of the proposed system for 5 G digital data transmission and reception, dispersion analysis over the length of fiber is performed. Furthermore, its performance for various digital modulation schemes is discussed.

Filter-free image-reject microwave photonic downconverter based on cascaded modulators.

As essential equipment of the receiver, a novel filter-free image-reject mixer based on a Mach-Zehnder modulator (MZM) and a polarization-division multiplexing Mach-Zehnder modulator (PDM-MZM) is proposed and experimentally demonstrated in this paper. The received radio frequency signal is applied to the MZM, and quadrature local oscillator signals are sent to the PDM-MZM, which includes two submodulators in parallel. After a polarization controller and a polarization beam splitter, quadrature intermediate frequency (IF) signals are obtained by two photodetectors. Image rejection is implemented by combining quadrature IF signals via an electrical 90° hybrid coupler. The scheme uses no filter, so the working frequency can be widely tuned and effective spectrum utilization is achieved. Experimental results verify that image rejection ratios can reach 50dB. Moreover, the variation of the conversion gain is lower than 2dB.

基于受激布里渊散射效应的微波光子下变频系统

基于受激布里渊散射效应的微波光子下变频系统

Microwave Photonic Downconversion With Improved Conversion Efficiency and SFDR

In this paper, we report a novel approach of microwave frequency downconversion with improved conversion efficiency and high dynamic range, using two different configuration schemes. The first proposed scheme is designed by using a dual-parallel dual-drive Mach–Zehnder modulator and the second one using dual-parallel dual-phase modulator. The radio frequency (RF) message signal and the local oscillator (LO) signal are feeding these two parallel connected modulators. By using a tight control of the system parameters, we have reported an effective optical carrier suppression, resulting in high conversion efficiency. We show that when the link is amplified, the relation between $m_{\mathrm {LO}}$ and $m_{\mathrm {RF}}$ plays a vital role and gives a high value of conversion efficiency, where key parameters lead to the LO and RF modulators modulation index. The conversion efficiency is improved by 5.72 dBm, compared with previously published work using DP-MZM, and 28.4 dBm, compared with the cascaded connected modulator. An experimental demonstration of a proof of concept is also carried out where the intermediate frequency to noise ratio of 69.5 dB is reported.

Dual-parallel Mach-Zehnder modulator based microwave photonic down-conversion link with high dynamic range

With the rapid development of the microwave photonic communication technology, the frequency of the microwave signal is expanded to the Ka waveband, since most of low frequency bands are occupied. However, the current commercial detectors and signal processing modules are limited by bandwidth. Therefore, the traditional method of directly detecting the microwave signals cannot meet the actual demands. It is essential to achieve the microwave photonic down-conversion from the high frequency microwave signal (~10 GHz) to the lower frequency signal (~100 MHz). Meanwhile, the down-conversion low frequency signal can be processed by the existing mature technology and low cost devices. The microwave down-conversion link can effectively avoid leaking the local oscillator, and it possesses many advantages such as high bandwidth and spurious free dynamic range, low loss and low noise. In this paper, a microwave photonic down-conversion system is presented based on the integrated dual-parallel Mach-Zehnder modulator (DPMZM) to increase the spurious-free dynamic range as well as conversion efficient of microwave photonic link. The integrated DPMZM is mainly comprised of two intensity modulators (MZM-a and MZM-b), and a phase shifter. The radio frequency (RF) signal is loaded into DPMZM to modulate the optical signal. The local oscillator is loaded into the MZM-a to produce the 1st local oscillator sideband, and two RF signals are fed to the MZM-b to form the 1st RF signal sideband. The direct current bias of the DPMZM is adjusted to output a high carrier suppressed double sideband (DSB) signal. The erbium-doped fiber amplifier is used to increase the power of light to match the power range of the detector. The RF signal sideband and local oscillator sideband are mixed to produce the beat frequency, and the frequency down-conversion can be achieved. The principle of frequency down-conversion is elaborated by theoretical analysis. The conversion efficiency and spurious free dynamic range are analyzed and simulated. On this basis, the microwave photonic link of frequency down-conversion is built. The performance of the system is tested. The ratio of optical carrier power to sideband power of the DSB signal is 26 dB. The experimental result shows that the conversion efficiency is 7.43 dB and spurious-free dynamic range is 110.85 dB/Hz2/3. The down-conversion method based on the DPMZM can optimize the output spectrum of the sideband. The structure of system is simple and easy to implement, so it is a good option for improving the conversion efficiency and spurious-free dynamic range.

基于强度-相位级联调制的微波光子下变频法

基于强度-相位级联调制的微波光子下变频法

High-Efficiency Photonic Microwave Downconversion With Full-Frequency-Range Coverage

Microwave frequency downconversion is optically implemented by using two cascaded polarization modulators (PolMs), characterized by full-frequency-range coverage and high conversion efficiency. In this proposed approach, the incident radio-frequency signal (RF) and the local oscillator signal (LO) are applied to the first PolM at the transmitter and the second one at the receiver, respectively. Effective optical carrier suppression can be achieved using the cascaded PolMs, whereas the optical sidebands induced by the RF and the LO signals remain unchanged. Since no additional optical filter is needed, the lower operation frequency limit in other approaches with an optical filter is eliminated, such that a full-frequency-range coverage is ensured in this approach. Meanwhile, the use of optical carrier suppression (OCS) enables high conversion efficiency for microwave downconversion. In the proof-of-concept experiments, the conversion efficiency is improved by over 20 dB within the frequency range from 2 to 15 GHz, as compared to those of cascaded modulators without OCS. Both the upper and the lower limits of such a frequency range can be greatly extended when test instruments with full frequency range are used.

Microwave Photonic Downconversion Using Phase Modulators in a Sagnac Loop Interferometer

A new high conversion efficiency and wideband microwave photonic downconverter with infinite isolation between the RF and LO port, which enables the RF and LO to be located at different locations, is presented. It is based on two traveling wave electrooptic phase modulators inside a Sagnac loop interferometer. No dc bias voltages are required and there are no bias drift issues. High conversion efficiency downconversion is obtained by optical carrier suppression inherent from the Sagnac loop structure, which allows high-amplitude RF and LO sidebands into the photodetector. The microwave photonic downconverter topology can be extended to have multiple RF channels using a wavelength division multiplexing technique in which the phase modulators driven by the RF signals can be located in different remote locations. Experimental results are presented which demonstrate wideband operation from 5 to 20 GHz and over 26 dB conversion efficiency improvement compared to the conventional dual-series MZM-based microwave photonic downconverter.

Polarization-insensitive photonic microwave downconversion

A polarization-insensitive photonic microwave downconverter is proposed and demonstrated, which is comprised of a polarization beam splitter, two Mach-Zehnder modulators (MZMs), and a balanced photodetector. By biasing the MZMs at the quadrature bias points with opposing modulation slopes, the performance of the proposed photonic microwave downconverter is almost independent of the polarization state of the optical microwave signal for down conversion. An experiment is performed, which shows that the polarization dependent loss of the proposed downconverter is less than 0.06dB. The downconverter is also evaluated in a radio-over-fiber link. A 20GHz RF signal with 20MBaud 16 quadrature amplitude modulation baseband data is successfully downconverted to a 1GHz IF signal. When the polarization state of the input optical microwave signal is adjusted, the variation of the error vector magnitude of the downconverted signal is less than 0.4%.

High-Performance Photonic Microwave Downconverter Based on a Frequency-Doubling Optoelectronic Oscillator

Photonic microwave downconversion based on an optoelectronic oscillator (OEO) is interesting because the local oscillator signal is directly extracted from the RF signal, but some of the frequency components in the RF signal would leak to the oscillation signal due to the limited rejection ratio of the electrical bandpass filter in the OEO, which degrades the downconverted signal. In this paper, a high-performance photonic microwave downconverter based on a frequency-doubling OEO (FD-OEO) is proposed and demonstrated to avoid the direct degradation from the RF signal. A 20-GHz RF signal with 1-Gb/s data modulation is successfully downconverted by the FD-OEO. The phase noise at 10-kHz frequency offset of the extracted RF carrier by the FD-OEO is 14 dB lower than that extracted by a conventional OEO, and the receiver sensitivity of the downconverted signal has a 1.173-dB improvement. The downconverter needs only low-frequency devices, which may find application in phased-array antenna arrays, electronic warfare receivers, avionics, and wireless communication systems.