Single-electrode Mach-Zehnder Modulator Research Articles

Bidirectional and simultaneous transmission of baseband and wireless signals over RSOA based WDM radio-over-fiber passive optical network using incoherent light injection technique

Reflective semiconductor optical amplifier (RSOA) based wavelength division multiplexed radio-over-fiber passive optical network (WDM−RoF−PON) has been proposed and demonstrated, to transmit 2.5Gbps baseband (BB) and 1.25Gbps wireless data in downstream and 1Gbps BB data signal in upstream over 25-km single-mode fiber (SMF), and wireless downstream signal over 25-km SMF as well as 5.2m free space in air. In the downstream, 2.5Gbps BB data and 1.25Gbps wireless data are modulated using single-electrode Mach–Zehnder modulator (SD-MZM) based on double-sideband with optical carrier suppression (DSBCS) scheme and simultaneously transmitted by incoherent light injection technique and employing fiber Bragg grating (FBG) at the base station. RSOA is utilized at the user end to reuse the carrier for uplink transmission. High receiver sensitivity, low bit-error-rate (BER) and excellent eye-diagram, eye height are achieved in our proposed network system and the results affirm the acceptability of proposed RSOA based WDM−RoF−PON.

Demonstration of optical frequency quadrupling combined with direct/external signal double-sideband suppressed-carrier modulation

This study experimentally demonstrates the performance of optical frequency quadrupling generation and base-band signal up-conversion techniques based on the cascaded single-electrode Mach–Zehnder modulator (SEMZM) using different signal modulation schemes. The optical signals in microwave band with double-sideband suppressed-carrier (DSB-SC) modulated format exhibit that the receiver sensitivity and the spectral efficiency are maximized and the power penalty over long-distance delivery is minimized. A simple configuration and low-frequency bandwidth requirement for both electrical and optical components in the proposed schemes also are demonstrated.

Simple 60-GHz Radio-over-Fiber System with Transmission Distance Improvement Employing Signal-to-Signal Beat Noise Compensation

We propose a simple 60-GHz RoF system using one single-electrode Mach-Zehnder modulator (MZM). By choosing proper carrier frequencies of two MZM driving signals, fiber transmission distance can be extended up to 12 km. Compared with conventional intensity modulation with direct detection using 60-GHz MZM or electro-absorption modulator (EAM), the proposed RoF system can support longer fiber transmission distance (up to 12 km) and has less bandwidth requirement of optical orthogonal frequency-division multiplexing (OFDM) transmitter (34 GHz vs. 64 GHz). However, the generated 60-GHz OFDM signal will have beat noise after square-law photo-detection. In this paper, the beat noise is analytically analyzed. Hence, the beat noise mitigation algorithm with the beat noise re-construction technique is proposed and utilized to reduce beat-noise-induced interference and improve signal-to-noise ratio (SNR). 60-GHz 13.75-Gbps quadrature phase shift keying (QPSK) and 20.625-Gbps 8-quadrature-amplitude-modulation (QAM) OFDM signals with 3-m wireless transmission are experimentally demonstrated and transmitted over 12-km and 6-km single-mode fiber, respectively.

Simple 14-Gb/s Short-Range Radio-Over-Fiber System Employing a Single-Electrode MZM for 60-GHz Wireless Applications

This paper demonstrates the feasibility of a simple multigigabit-per-second (Gbps) radio-over-fiber (RoF) system employing multilevel orthogonal frequency-division-multiplexing (OFDM) signal modulation at 60 GHz and a single-electrode Mach–Zehnder modulator (MZM). In this paper, the impact of fiber chromatic dispersion and OFDM beat noise on the performance of the RoF system are investigated by theoretical analysis, VPI WDM-TransmissionMaker simulation and experimental demonstration. A 13.875-Gb/s QPSK OFDM signal occupying the full 7-GHz license-free band at 60 GHz with frequency multiplication for the RoF link is demonstrated. After 3 km of standard single-mode fiber transmission with no dispersion compensation, the power penalty is less than 3 dB.

Transmission of Wireless and Wired Services Employing a Simple System Architecture

This letter presents a novel modulation approach for simultaneous generation and transmission of optical radio-frequency (RF) wireless vector signal and baseband (BB) wireline signal using a single-electrode Mach-Zehnder modulator. Based on a double sideband with carrier suppression scheme and properly predistorted driving vector signal, a 2.5-Gb/s quadrature phase-shift keying (QPSK) signal at 60 GHz is generated with a 1.25-Gb/s BB ON-OFF-keying (OOK) signal. The proposed system can carry higher spectral efficiency vector signals and needs no optical filter to separate the BB and RF signals at remote nodes. Moreover, optical RF signal generation with frequency doubling is also achieved to reduce the bandwidth requirement of the transmitter. After transmission over 25-km single-mode fiber, the power penalties of the generated QPSK and OOK signals are about 4 and 0.1 dB, respectively.

A Full duplex radio-over-fiber link with Multi-level OFDM signal via a single-electrode MZM and wavelength reuse with a RSOA

This work demonstrates the feasibility of a full duplex Radio-over-fiber (RoF) link employing multi-level OFDM signal via a single-electrode Mach-Zehnder modulator and wavelength reuse for uplink utilizing a reflective semiconductor optical amplifier (RSOA). A High spectral efficiency 5-Gb/s 16-QAM OFDM signal with frequency multiplication for the RoF downstream link is demonstrated, and negligible penalty is achieved after 25-km standard single mode fiber transmission. Furthermore, wavelength reuse for a 1.25-Gb/s OOK signal via a RSOA for the upstream link is also demonstrated with a receiver penalty of less than 0.5 dB following 25-km SMF transmission.

Novel Optical Vector Signal Generation With Carrier Suppression and Frequency Multiplication Based on a Single-Electrode Mach–Zehnder Modulator

This investigation presents a novel modulation approach for generating optical vector signals using frequency multiplication based on double sideband with carrier suppression. A single-electrode Mach-Zehnder modulator is biased at null point with a driving signal consisting of a 10-GHz sinusoidal signal and a 5-GHz sinusoidal signal modulated with 1.25-Gb/s on-off keying, 1.25-Gb/s binary phase-shift keying data, or 625-MSym/s quadruple phase-shift keying data. After square-law photodetection, a 1.25-Gb/s radio-frequency signal at a sum frequency of 15 GHz is generated. After transmission over 50-km single-mode fiber, the power penalty of all three modulation formats is under 0.2 dB.

Impact of Nonlinear Transfer Function and Imperfect Splitting Ratio of MZM on Optical Up-Conversion Employing Double Sideband With Carrier Suppression Modulation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <?Pub Dtl=""?>Generation of optical millimeter-wave (mm-wave) signal using a Mach–Zehnder modulator (MZM) based on double-sideband (DSB), single-sideband (SSB), and double-sideband with carrier suppression (DSBCS) modulation schemes have been demonstrated for various applications, such as broadband wireless signals or optical up-conversion for wavelength-division-multiplexing (WDM) radio-over-fiber (RoF) network, wideband surveillance, spread spectrum, and software-defined radio. Among these schemes, DSBCS modulation offers the best receiver sensitivity, lowest spectral occupancy, the least stringent requirement of electrical bandwidth, and the smallest receiving power penalty after long transmission distance. Nonetheless, the inherent nonlinear E/O (electrical/optical) conversion response of a MZM is such that the signal quality of the optical mm-wave suffers. Fabrication tolerances make a balanced 50/50 splitting ratio of the MZM's y-splitter particularly difficult to achieve. As a result, imbalanced MZMs have a finite extinction ratio (ER) and degrade the optical carrier suppression ratio (OCSR) using DSBCS modulation. In this paper, the effect of the MZM nonlinearity and imbalanced y-splitter on optical mm-wave generation by DSBCS modulation is theoretically and experimentally investigated. A novel approach with better performance and greater cost-effectiveness than dual-electrode MZM (DD-MZM) is presented to realize a DSBCS modulation scheme based on a single-electrode MZM (SD-MZM). </para>

Simultaneous Generation of Baseband and Radio Signals Using Only One Single-Electrode Mach&amp;ndash;Zehnder Modulator With Enhanced Linearity

We experimentally demonstrate a simultaneous generation of baseband (BB) and RF signals, using only one single-electrode Mach-Zehnder modulator (SD-MZM) based on double-sideband with optical carrier suppression (DSBCS) scheme. With optimal modulation index (MI =V p-p/2Vpi) equal to 0.43 for driving MZM, the receiver sensitivity of the RF signal can have 1-dB improvement. Based on this result, only one SD-MZM is needed to generate optical microwaves using DSBCS scheme, thus eliminating the requirement of a high-cost dual-electrode MZM without degrading the signal performance. Following 75-km standard single-mode fiber, the power penalties of both BB and RF signals are less than 0.3 dB

Design and performance of the bidirectional optical single-sideband modulator

We present a detailed study of the design and performance of the bidirectional optical single-sideband modulator (BOSSM). This is a new scheme to achieve optical single-sideband modulation (OSSB) that uses a standard single-electrode Mach-Zehnder modulator (MZ-EOM) and passive fiber-optic components. The design is based on a novel technique to operate electrooptic modulators in which the radio frequency (RF) electrode is bidirectionally driven. The fundamentals of this bidirectional operation are analyzed thoroughly and it is found that it requires the use of a wide-bandwidth MZ-EOM with an electrode design that provides good velocity match between the optical and microwave modes. Deriving the expressions for the optical field and power at the output of the BOSSM, the OSSB operation is shown to be independent of the MZ-EOM bias. Therefore, the optical modulation depth at the output of the device can be enhanced using minimum transmission biasing to provide suppression of the optical carrier. Moreover, it is found that the second-order distortion is unaffected by the MZ-EOM bias; hence the technique can be applied to multi-octave bandwidth systems. Finally, the performance of the BOSSM is evaluated using a prototype based on a commercial 10 Gb/s MZ-EOM. The experimental characterization of the electrooptical parameters of this device reveals that the RF electrode design is not optimized for bidirectional operation. Therefore, the performance of the prototype is limited by the particular MZ-EOM deployed. However, sideband suppression over 10 dB is measured for most frequencies up to millimeter-waves, with peaks in the 20 dB to 30 dB range for narrow bands. This performance has enabled the demonstration of a 22-km fiber link transmitting a 29-GHz subcarrier conveying binary phase-shift keying modulated data at 622 Mb/s. The BOSSM reduces the dispersion-induced power penalty in the link to less than 1.5 dB. Furthermore, the bit error rate of the link is increased by five orders of magnitude using the carrier suppression technique.