Single Dual-parallel Mach-Zehnder Modulator Research Articles

Optical frequency comb generation based on dual-parallel Mach–Zehnder modulator and intensity modulator with RF frequency multiplication circuit

A new method of generating optical frequency comb by cascading a single dual-parallel Mach–Zehnder modulator and two intensity modulators is proposed. The intensity modulators are modulated by a frequency multiplication circuit of radio frequency. Theoretical model of the system is derived, and optical frequency comb with ultra-flatness and high side-mode suppression ratio can be obtained. The study results show that 72-line optical frequency comb with spectrum power variation of 0.26 dB, SMSR of 21 dB and frequency space of 4 GHz is gotten easily by adjusting the amplitude of radio frequency signal and the direct current bias of the modulators. The simulation result is in good agreement with the theoretical analysis model.

Photonic-assisted square waveform generation using a dual-parallel Mach–Zehnder modulator

A photonic approach to generating square waveforms using a single dual-parallel Mach–Zehnder modulator driven by a single-tone radio frequency signal is proposed and demonstrated. The two sub MZM are set to be biased at the minimum transmission point and the maximum transmission point, respectively. By simply adjusting the modulation index to have a proper value, optical intensity with expression corresponding to the Fourier expansion of a square waveform is obtained, and square waveforms will be generated. Neither an optical filter nor an electrical component of frequency multiplier or hybrid is needed to guarantee the simplicity and the wide working frequency range. A proof-of-concept experiment is taken. Both 1- and 4-GHz square waveforms fitting well with the ideal ones are successfully generated.

Wideband Doppler Frequency Shift Measurement and Direction Discrimination Based on a DPMZM

A wideband microwave Doppler frequency shift (DFS) measurement approach based on a single dual-parallel Mach–Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The light wave is modulated by the transmitted and echo signals in the DPMZM to generate carrier suppressed double sidebands signals. Based on the phase difference and powers of the upper bands and lower bands of the modulated signal, the DFS value, as well as the sign, can be measured. An experiment is carried out. The DFS from –100 to +100 kHz at the carrier frequencies of 10, 20, 30, and 39 GHz is accurately measured with errors of less than $5 \times {10^{ - 6}}$ Hz.

DUAL-CHIRP ARBITRARY MICROWAVE WAVEFORM GENERATION BY USING A DUAL PARALLEL MACH-ZEHNDER MODULATOR FEEDING WITH RF CHIRP SIGNAL

In this paper, dual-chirped arbitrary microwave waveform has been generated through photonics, incorporated with single dual parallel mach-zehnder modulator (DPMZM) inbuilt mach zehnder interferometer (MZI) structure. We have taken two cases of chirping, i.e., linear and nonlinear chirps. A case of linear chirping has been explored previously. However, to the best of the authors' knowledge effect of nonlinear chirping in this paper is evaluated for the first time. Other photonics approaches are also available, such as spectra shaping and wavelength to time mapping. But due to fixed spectral response of spectral shaper, center frequency of linear chirp generated waveform is fixed. To get large center frequency again we have to use large number of spectral shapers which will increase the system complexity. DPMZM avoids such difficulties. These MZMs are biased at the minimum transmission point to get carrier suppressed modulation. Product modulator (PM) is cascaded to the lower arm of DPMZM. Here by using DPMZM we get two advantages. First we have two complimentarily chirped microwave waveforms and second up conversion of the frequency of microwave carrier. A dual-chirped microwave waveform with centre frequency 6 GHz with bandwidth 200 MHz and 2 GHz is generated. The paper gives specific details about various performance parameters such as input signal frequency and power, output signal parameters viz output frequency, chirp rate, chirp bandwidth, time bandwidth product (TBW), etc. The overall model and its performance parameters are computed through MATLAB simulation.

A flexible and ultra-flat optical frequency comb generator using a parallel Mach–Zehnder modulator with a single DC bias

A flat optical frequency comb generator utilizing a single dual parallel Mach–Zehnder modulator (DPMZM) is detailed investigated both in theory and experiment. In the scheme, the two sub-modulators of DPMZM are biased at the maximum and minimum transmission points respectively. By adjusting the RF signals power, two optical frequency combs with even harmonics or odd harmonics can be generated. So at the end of DPMZM, 5 and 7-line flat OFCs with a side-comb suppression ratio (SCSR) higher than 18dB are theoretically and experimentally generated. The optical frequency comb generator scheme is relatively simple and valuable due to only one bias voltage may be controlled.

Dual-Chirp Microwave Waveform Generation Using a Dual-Parallel Mach-Zehnder Modulator

A photonic approach to generating a dual-chirp microwave waveform using a single dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. A dual-chirp microwave waveform can be used in a radar system to improve its range-Doppler resolution. In the proposed approach, a baseband single-chirp waveform is applied to one sub-Mach-Zehnder modulator (sub-MZM) in the DPMZM and a microwave carrier is applied to the other sub-MZM. By biasing the two sub-MZMs at the minimum transmission point to suppress the optical carrier, a dual-chirp microwave waveform with a central frequency upconverted to the frequency of the microwave carrier is generated. A theoretical analysis is performed, which is then verified by a proof-of-concept experiment. A dual-chirp microwave waveform at 6 GHz with a tunable bandwidth at 200 MHz and 2 GHz is generated.

A tunable optical frequency comb generator using a single dual parallel Mach–Zehnder modulator

Abstract A scheme of generating optical frequency combs (OFC) utilizing a single dual parallel Mach–Zehnder modulator (DPMZM) is detailedly investigated. Both the theoretical analysis and experimental results show that the generator is power efficient. Gaussian-shaped OFC and flat OFC with a tunable spacing, flexible line-number and high side mode suppression ratio (SMSR) are experimentally generated with relatively lower RF power.

Investigation on Nyquist pulse generation using a single dual-parallel Mach-Zehnder modulator.

The generation of Nyquist pulses with a dual parallel Mach-Zehnder modulator (DPMZM) driven by a single RF signal is demonstrated theoretically and experimentally. A complete theoretical analysis is developed and the limitation of the proposed scheme is also discussed. It is theoretically proved that Nyquist pulses with a spectrum of 5 flat comb lines can be generated using a single DPMZM, which is also verified with simulation. 7 flat comb lines in frequency domain can also be obtained if a large RF driving voltage is applied to DPMZM but the generated waveforms won't present a sinc-shape. This scheme is further investigated experimentally. 40 GHz Nyquist pulses with full-width-at-half-maximum (FWHM) less than 4.65 ps, signal-to-noise ratio (SNR) better than 29.5 dB, and normalized root-mean-square error (NRMSE) less than 2.4% are generated. It is found that a tradeoff exists between the insertion loss of the DPMZM and the deviation of generated pulses. The tunability of repetition rate is experimentally verified by generation of 1 GHz to 40 GHz Nyquist pulses with SNR better than 28.4 dB and NRMSE less than 6.15%.

A flexible waveforms generator based on a single dual-parallel Mach–Zehnder modulator

A new scheme of waveforms generator using a single dual-parallel Mach–Zehnder modulator (DPMZM) driven by a sinusoidal RF signal is proposed. By optimizing the working parameters of the DPMZM with a waveform generation algorithm, various waveforms, such as Gaussian, trapezoidal, triangular, sawtooth waveforms and sinc pulses, with a repetition rate of 10GHz are theoretically and experimentally generated. It is found that the similarity coefficient between the experimental results and the theoretical results is larger than 92%.

Generation of optical carrier suppressed-differential phase shift keying (OCS-DPSK) format using one dual-parallel Mach-Zehnder modulator in radio over fiber systems

We present and experimentally demonstrate a new method to generate optical carrier suppressed-differential phase-shift keying (OCSDPSK) modulation format in radio over fiber (RoF) systems. In our scheme, a single dual-parallel Mach-Zehnder modulator (DPMZM) is used to produce OCS-DPSK signal based on amplitude shift keying (ASK) to DPSK format conversion by suppressing the spectral tones of an OCS-ASK signal.

Performance Investigation of a Multiformat Transmitter With Pulsewidth Tunability

We propose and demonstrate a novel transmitter that enables versatile format generation with pulsewidth tunability. The transmitter is based on a single dual-parallel Mach-Zehnder modulator. By simply switching the driving and biasing conditions of the modulator, duobinary, return-to-zero alternate mark inversion and Manchester formats are obtained in a similar transmitter configuration. The back-to-back and transmission performances of the generated signals are investigated by experiments