Parallel Mach-Zehnder Modulator Research Articles

A review on photonic‐assisted dual‐chirp microwave waveform generation methods

AbstractIn recent times, photonic synthesis and processing of arbitrary microwave waveforms have gained interest due to their high frequency and huge time–bandwidth product. This study reviews methods for producing dual‐chirp microwave waveforms, focusing mostly on system topologies based on external modulation techniques, such as cascaded Mach–Zehnder modulator (MZM), dual parallel MZM, and dual polarized MZM. Other photonic approaches, like using semiconductor laser and optical heterodyne detection methods, are also discussed. These techniques are preferable because of high frequency, enhanced time–bandwidth product, greater chirp rate, and many more advantages. Additionally, the difficulties associated with integrating the systems into real‐world applications are also addressed.

Performance study of microwave photonic links by considering the effect of phase shifters and bias conditions on dual-drive dual parallel Mach–Zehnder modulator

Abstract This paper presents the performance analysis of different schemes for generating linearized photonic signal by varying phase shifter arrangements of a dual-drive dual parallel Mach–Zehnder modulator (DD-DPMZM). The RF signals at the electrodes of sub-modulators of DD-DPMZM are fed using different phase angles to generate optically modulated signals in the output. The proposed system consists of a DD-DPMZM and phase shifters. Spurious free dynamic range (SFDR) is evaluated for different configurations of sub modulators in upper and lower arm of DD-DPMZM. SFDR of 135.6 dB Hz4/5 is obtained for quadrature and optical carrier suppression modulation in upper and lower submodulators by suppressing third order intermodulation distortion completely. It is found to be high performance configuration for dual parallel Mach–Zehnder modulator based linear microwave photonic link.

Photon Generation Scheme of 32‐Fold Millimeter‐Wave Signal Based on Mach‐Zehnder Modulator

AbstractThis paper proposes a 32‐tupling frequency millimeter‐wave (MMW) filter‐free system based on four Mach‐Zehnder Modulators (MZM) connected in parallel and cascaded with a simple radio‐fiber (RoF) link structure. The four MZMs are all at the maximum transmission point (MATP), and the radio frequency (RF) driving voltage phase difference between MZMs is π /2. The center carrier is suppressed by using an optical attenuator (OATT) and an optical phase shifter (OPS). Two parallel MZMs can generate ±8th order and ±12th order optical sidebands, and the ±4th order optical sidebands can be suppressed by adjusting the modulation index m of the MZM, using cascaded two dual‐parallel MZMS(DPMZM) and the phase difference of the RF signal source is π/4 to generate ±16th order optical sidebands. The theoretical analysis and simulation experiments are performed for the scheme proposed in this paper. The results show that the simulated and theoretical values of the optical sideband suppression ratio (OSSR) for ±16th order optical sideband signals are 60.02 and 59.96 dB, respectively, and the simulated and theoretical values of the RF sideband suppression ratio (RFSSR) for the 32‐tupling MMW signal are 56.34 and 53.94 dB, respectively.

Design and investigation of filterless sixtuple RoF upconversion system with improved sideband to carrier suppression ratio using MZM extinction ratio variance

Abstract In this work, millimeter wave generation of sixtuple frequency scheme using dual parallel Mach–Zehnder modulator configuration has been investigated. The proposed scheme is mathematically analyzed and its performance is evaluated using software optisystem v.18. The vital parameters of both Mach–Zehnder modulator and phase of radio frequency local oscillator are properly adjusted for upconversion of 10 GHz radio frequency drive signal into 60 GHz mm wave. The impact of Mach–Zehnder modulator extinction ratio on radio frequency sideband suppression ratio, optical sideband suppression ratio and third sideband to carrier suppression ratio, is evaluated. An improved 63 dB third sideband to carrier suppression ratio is achieved at increased extinction ratio of Mach–Zehnder modulator. Impact of bias point drift and electrical phase shift on sideband suppression ratios are evaluated. Further, millimeter wave signal of 6–60 GHz tunability is realized by applying radio frequency local oscillator signal from 1 to 10 GHz.

Simultaneous Photonics Generation of Multiple Chirp Rate Microwave Waveform With Manifold Frequency Multiplying Capability by Using Triple Parallel Mach-Zehnder Modulators

Simultaneous Photonics Generation of Multiple Chirp Rate Microwave Waveform With Manifold Frequency Multiplying Capability by Using Triple Parallel Mach-Zehnder Modulators

Silicon-Organic Hybrid Electro-Optic Modulator and Microwave Photonics Signal Processing Applications.

Electro-optic modulator (EOM) is one of the key devices of high-speed optical fiber communication systems and ultra-wideband microwave photonic systems. Silicon-organic hybrid (SOH) integration platform combines the advantages of silicon photonics and organic materials, providing a high electro-optic effect and compact structure for photonic integrated devices. In this paper, we present an SOH-integrated EOM with comprehensive investigation of EOM structure design, silicon waveguide fabrication with Slot structure, on-chip poling of organic electro-optic material, and characterization of EO modulation response. The SOH-integrated EOM is measured with 3 dB bandwidth of over 50 GHz and half-wave voltage length product of 0.26 V·cm. Furthermore, we demonstrate a microwave photonics phase shifter by using the fabricated SOH-integrated dual parallel Mach-Zehnder modulator. The phase shift range of 410° is completed from 8 GHz to 26 GHz with a power consumption of less than 38 mW.

Sagnac Loop Based Broadband Self-Interference Cancellation and Down-Conversion for Distributed Antenna Systems

Focusing on distributed antenna systems, we propose a photonics-assisted self-interference cancellation and down-conversion method based on a Sagnac loop structure. Two inversely cascaded modulators form a Sagnac loop through polarization multiplexing. To support in-band full duplex (IBFD) communication, a double parallel Mach–Zehnder modulator (DPMZM) operated in a clockwise direction is used as a self-interference canceller (SIC) to achieve the phase conversion in the optical domain. Another MZM modulator working in the counterclockwise direction is used to modulate the local oscillation (LO) signal for frequency down-conversion. The adjustment of bias voltage is analyzed to optimize the conversion efficiency of the system. The power fading effect generated by fiber dispersion is compensated by a polarization-sensitive phase modulator (PS-PM). The experimental results show that the average cancellation depth is 56.4 dB at a single frequency in the operating frequency range of 6–22 GHz, and 29.1 dB and 23.7 dB for 20 MHz and 100 MHz bandwidth signals, respectively. In addition, the error vector map is improved from 16.50% to 6.26% after dispersion compensation. The self-interference cancellation, down-conversion and dispersion compensation are integrated in a microwave photonics link. Two cascaded modulators are equivalent to a parallel structure by the Sagnac loop, simultaneously ensuring high LO isolation and conversion efficiency. The proposed method provides an alternative for IBFD-based distributed antenna communication applications.

Comparison of performance for third order immune photonic transmission link incorporating phase shifters and biased optimized dual parallel Mach–Zehnder modulator

Abstract This paper presents a comprehension on the linearization arrangements achieved through dual drive dual parallel Mach–Zehnder (DD-DPMZM) by changing bias voltages of sub-modulators and adjusting phases of RF signals. These arrangements comprise of a DD-DPMZM and electric phase shifters. For single sideband (SSB) modulation in sub-modulators of DD-DPMZM, power at intermodulation is found to be 43 dB and 61 dB for the linearized and convention single modulator link respectively. Thus, 28 dB of improvement in suppression of third order intermodulation distortion is reported for the first arrangement of linearization. For quadrature modulation in upper MZM and optical carrier suppression (OCS) modulation in lower modulator, almost complete suppression of IMD3 terms are demonstrated and found to be better performance arrangement for bias optimized dual parallel Mach–Zehnder modulator based linearization link.

Measurement and multiplexing of ultra-low duty cycle Nyquist pulse sequences.

In this paper, we propose a novel, to the best of our knowledge, method to our knowledge for generating and accurately measuring Nyquist pulse sequences with an ultra-low duty cycle of only 0.037, which breaks the limitations caused by the noise and bandwidth of the optical sampling oscilloscope (OSO) by using a narrow-bandwidth real-time oscilloscope (OSC) and an electrical spectrum analyzer (ESA). By this method, it is found that the bias point drift of the dual parallel Mach-Zehnder modulator (DPMZM) is the main cause of the distortion of the waveform. In addition, we increase the repetition rate of Nyquist pulse sequences by a factor of 16 by multiplexing the unmodulated Nyquist pulse sequences.

The performance of millimeter-wave over fiber using electro absorption modulator and avalenche photodiode

In this paper, a parallel MZM and a quadrupling frequency technique are used to produce a 72 GHz mm-wave. The determined optical sideband suppression ratio (OSSR) is 71 decibels. This mm-wave signal's performance is compared to that of two optical modulators, the Mach Zehnder Modulator (MZM) and the Electro Absorption Modulator (EAM) as well as two different kinds of photodiodes, the Avalanche Photodiode (APD) and the PIN-PD. When using the EAM modulator, the maximum Q factor for 80 km is almost 20, but when using MZM, it is only 2.3. The performance of the generated mm-wave was then investigated using two different types of PD, PIN and APD, as optical receivers to achieve the best result in terms of signal quality. When compared to PIN-PD, APD improves the power of the received 72 GHz signal by 35%. The system's ability to carry a higher data rate is tested by successfully varying the bit rate up to 10 Gb/s over a distance of 20 km.

Performance investigation of DPMZM based RoF system by employing PIN and APD photodetector

Abstract As per the increasing demand of users, the wireless network fulfils significant challenges in terms of capacity, data rate, reduced environmental impact and better receiver performance. Radio over fiber (RoF) is the technique by which radio signal is modulated over the optical fiber link. The functioning of RoF is dependent on the optical modulator, optical fiber and photodetector. In this paper, dual parallel Mach–Zehnder modulator (DPMZM) is used, which gives good results against intermodulation distortion (IMD) errors. In order to investigate the receiver performance, positive-intrinsic-negative (PIN) and avalanche photodiode (APD) photodetectors are utilized at the receiver end. The analytical analysis of DPMZM based RoF system is analyzed, and the simulation model is implemented using OptSIM software, including PIN and APD photodetectors. The performance is scrutinized against various optical fiber lengths. The performance of the proposed model is analyzed and investigated by the presence of desired components and distorted (IMD) components for 1 and 5 km optical fiber distance between the control station and base station.

Generation of Therahertz Wave with Frequency 32-Tupling by Four Mach-Zehnder Modulators in Parallel

A new method for the generation of terahertz wave with frequency 32-tupling adopting four Mach-Zehnder modulators connected in parallel is presented. The four MZMs can be regarded as two double parallel Mach-Zehnder modulators (DPMZMs) connected in parallel. When the difference of the initial phases of the radio frequency (RF) driving signals between two MZMs in the DPMZM is π/2, the signal from the DPMZM are the optical sidebands of ±4n order. When the difference of initial phase of the RF signals between the two DPMZMs is π/4, the output signals from the two DPMZMs are the optical sidebands of ±8n order, in which the carrier is cancelled by an adjustable optical splitter, the optical sidebands of ±8th order are restrained and the optical sidebands of ±8n (n > 2) order are ignored by setting the modulation index of MZM at a special value, the main optical sidebands left are ±16th order. When the ±16th order optical sidebands are injected the photodetector (PD), the 32-tupling frequency terahertz wave is generated. Principle analysis and simulation test indicate that the optical sideband suppression ratio (OSSR) and the RF spurious suppression ratio (RFSSR) are 46.82 dB, 46.25 dB and 40.8 dB, 42.3 dB, respectively. In addition, the impacts on the OSSR and RFSSR are studied when the values of device parameters deviate from their design values.

A Simple Photonics-Based Measurement Method for Microwave DFS and AOA

This article put forwards a simple microwave photonics measurement method for microwave doppler frequency shift (DFS) and angle of arrival (AOA), which obtains the information conveniently and precisely by comparing the frequency and phase shift between two channels signals. The DFS direction can be judged more intuitively thanks to the introduction of the reference signal. The system uses two parallel dual parallel Mach-Zehnder modulators (DPMZMs) for carrier suppression single-sideband (CS-SSB) modulation. A proof-of-concept experiment was taken, showing that during ±100 kHz, the DFS measurement error is <±0.1 Hz over a 40 GHz frequency range as well as power sensitivity is down to −50 dBm. What is more, the measurement error of AOA is < ±1° from 0° to 90°. This simple system acquits excellent width band performance without the optical filter, providing a reliable and more conducive to human-computer interaction solution for future measurement and sensing applications.

Tuneable Microwave Photonics Filter Based on Stimulated Brillouin Scattering With Enhanced Gain and Bandwidth Control

A Tuneable Microwave Photonics Gain Filter (TMWPF) is proposed based on Stimulated Brillouin Scattering (SBS). The TMWPF configuration exhibits a gain of 70dBm and tuneable bandwidth control which makes it attractive for applications requiring high gain and bandwidth variations with high precision. The proposed TMWPF configuration employs a tuneable laser, an Erbium-Doped Fibre Amplifiers (EDFA), Radio Frequency (RF) mixers, an RF Amplifier (RFA), Single Mode Fibre (SMF) and Gallium Arsenide (GaAs) I-Q Dual parallel Mach-Zehnder Modulator (DPMZM). The modulation scheme performed by I-Q DPMZM is controlled by a voltage bias controller. The performance of the filter is compared whilst using LiNbO3 Phase Modulators (PMs) and Intensity Modulators (IMs) instead of GaAs I-Q DPMZM. The TMWPF delivers 44dBm, 57dBm & 44dBm of gain for I-Q DPMZM, PM, and IM, respectively. The use of RFA resulted in a total gain of 62dBm, 69dBm & 52dBm for I-Q DPMZM, PM and Amplitude Modulators (AM), respectively. This configuration exhibits high Q, tuneable bandwidth by employing stokes SBS gain, RF mixer and RFA. The bandwidth of the filter is varied from 20MHz to 40MHz. The operation principle of the TMWPF is based on SBS stokes gain. By controlling the bias point of the I-Q DPMZM, the operating point can be varied between PM and IM allowing 6dBm gain control and the choice of PM or IM for specific applications. This gives improved filter performance. The full control of TMWFP's gain is obtained by using EDFA. The EDFA controls the power of the tuneable laser pump. The control challenges of the proposed TMWPF along with improvement enhancements are reported. The proposed TMWPF exhibits tuneability of 32GHz in RF domain, and 40GHz in optical domain. To the best of our knowledge, this TMWPF exhibits the highest reported gain.

A dual parallel Mach–Zehnder modulator linearization scheme based on 90° phase shifters

Abstract In this paper, a dual-drive dual-parallel Mach–Zehnder Modulator based linearization scheme is implemented by utilizing only two phase shifters and comprehensively demonstrated for a photonic transmission link. Third order intermodulation distortion is suppressed by adjusting angles of electrical phase shifters i.e. π/2 and−π/2 and a non-linear distortion immune system can be proposed for microwave photonic link. A complete suppression in intermodulation terms and 20.8 dB enhancements are found in spurious free dynamic range (SFDR). SFDR reaches 135.6 dB Hz4/5 by suppressing major spurious contributors of third order intermodulation distortions in optical domain only which ensures the improvement in performance of link against non-linear terms.

Design and Manufacture of Traveling-wave Electro-optic Modulator for X-band LFM Signal Generation

In this paper, a photonic-based microwave system technology is described, and a traveling-wave electro-optic modulator is designed and manufactured as a key component. The fabricated modulator is composed of a metal diffusion waveguide for optical transmission and a planar waveguide electrode on lithium niobate substrate for microwave transmission. The electro-optic response bandwidth of I and Q channels in a fabricated dual parallel Mach-Zehnder modulator were measured for 27.67 and 28.11 GHz, respectively. Photonic four times up-converted X-band frequency and linear frequency modulated signal were confirmed using the fabricated electro-optic modulator by S-band input signal. The confirmed broadband signal can be applied to a microwave system for surveillance and high-resolution ISAR imaging.

A photonic transmission link with enhanced dynamic range by incorporating phase shifters in dual drive dual parallel Mach–Zehnder modulator

Abstract A linearization scheme is proposed for microwave photonic link to enlarge spurious free dynamic range using a dual-electrode dual parallel Mach–Zehnder modulator (MZM). This scheme employs phase control method to improve performance of the link by adjusting phase of radio frequency (RF) signals and bias voltages of optical modulator. Optical single sideband modulation is achieved through sub-modulators of dual parallel MZM which increases efficiency of the link. The simulated results show that third order intermodulation distortion is suppressed by 28 dB when the input RF signals are 9.1 and 9.5 GHz and noise floor is at −161 dBm/Hz. The spurious free dynamic range is also improved by 12.6 dB.

고해상도 ISAR 영상을 위한 광자 기반 FMCW 송수신 시스템 설계

This paper proposes a design for a photonics-based radar system for high-resolution inverse synthetic-aperture radar (ISAR) images. The proposed radar system can derive broadband characteristics using optical elements, such as phase modulator, laser source, and dual parallel Mach-Zehnder modulator (DPMZM). The detection performance and ISAR images for the target are observed according to the bandwidth of the radar system using modeling and simulation (M&amp;S) for the proposed radar system. To verify the effectiveness of the bandwidth of the radar system, the proposed radar system are fabricated, and its performances are measured using a small drone in a practical environment. The results prove that the proposed FMCW radar system is a suitable candidate to overcome the limitations of bandwidth and high resolution.

Reconfigurable photonic binary phase-coded microwave signal generator with fundamental/subharmonic carrier frequency.

A reconfigurable photonic binary phase-coded microwave signal generator with fundamental/subharmonic carrier frequency is proposed and experimentally investigated based on a dual-electrode dual parallel Mach-Zehnder modulator (DE-DPMZM). The local oscillator (LO) signal and coding signal are intensity modulated and phase modulated, respectively, on the two arms of the DE-DPMZM. The bias voltage of the intensity modulator is set to the quadrature or maximum working points to produce fundamental or subharmonic frequency, respectively. By precisely adjusting the amplitude of the LO signal and the bias voltage of the parent modulator, the light carriers of both arms of the DE-DPMZM can be eliminated. After detection, binary phase-coded microwave signal with frequency equal to or twice the frequency of the LO signal can be generated. The proposed system has a simple structure, high reconfigurability, and good frequency tunability due to its avoidance of using optical filters. In the experiment, phase-coded microwave waveforms at 6 GHz and 11 GHz are generated by using 6 GHz and 11 GHz LO signals or 3 GHz and 5.5 GHz LO signals, respectively. Meanwhile, the performance is evaluated in terms of phase recovery accuracy and pulse compression capability. The experimental results show that the proposed generator has high peak-to-sidelobe ratio, which has practical significance for radar detection of weak targets.

A Novel Decoupling Bias Control Technique for Dual Parallel Mach-Zehnder Modulator

A Carrier Suppressed Single Sideband(CS-SSB) modulation decoupling control technique based on Dual Parallel Mach-Zehnder Modulator (DPMZM) is proposed to solve the problem that the bias point of the DPMZM leads to the degradation of the modulation signal under the influence of ambient temperature, fiber coupling loss or other factors. This technique introduces three non-disturbing dithering voltages at the bias end of the modulator and detects the power ratio of the optical signal at the output end to realize CS-SSB modulation. Experimental results show that the proposed technique can effectively stabilize Optical Sideband Suppression Ratio(OSSR) above 24dB. This letter also proves that this technique is feasible for other modulators and has great practical value in the microwave photonic system.