Optical Sideband Suppression Ratio Research Articles

Optical frequency multiplication using residual network with random forest regression

In this work, we present a method for optical frequency multiplication utilizing a hybrid deep learning approach that integrates the Residual Network (ResNet) with the Random Forest Regression (RFR) algorithm. Three different frequency multiplication modulation schemes are adopted to illustrate the method, which can obtain suitable parameters for these schemes. Based on the parameters predicted by the algorithm, the 8-tupling, 12-tupling, and 16-tupling mm-wave signals are generated by numerical simulation. The simulation results show that for 8-tupling frequency multiplication, an OSSR (optical sideband suppression ratio) is 30.73 dB and an RFSSR (radio frequency spurious suppression ratio) of 80 GHz is 42.29 dB. For 12-tupling frequency multiplication, the OSSR is 30.09 dB, and the RFSSR of the 120 GHz mm wave is 36.21 dB. For generating 16-tupling frequency mm-wave, an OSSR of 29.86 dB and an RFSSR of 34.52 dB are obtained. In addition, the impact of amplitude fluctuation and bias voltage drift on the quality of mm-wave signals is also studied.

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.

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.

Radio-over-fibre for generation and transmission32-tupling frequency optical millimeter wave with polarization modulators

Radio-over-fibre for generation and transmission32-tupling frequency optical millimeter wave with polarization modulators

Generation of frequency 16‐tupling millimeter wave without filtering based on cascaded Mach–Zehnder modulator

AbstractA scheme of generating millimeter‐wave signals with 16 times frequency using a cascaded Mach–Zehnder modulator (MZM) is proposed. Optical delay lines (ODLs) are used to place between cascaded MZMs, two MZMs work at the maximum transmission point. By controlling the modulation index of the MZM and the delay of the ODL, 0‐order, ‐order, and ‐order sidebands can be generated. The optical phase shifter and attenuator are adjusted to eliminate the 0‐order sideband, and the photodetector output generates a frequency 16‐tupling millimeter wave (MMW). In the simulation platform, a 160‐GHz MMW signal can be obtained by taking a 10‐GHz radio frequency signal as the driving signal of two MZMs. The optical sideband suppression ratio is 29.92 dB, and the radio frequency sideband suppression ratio is 24.89 dB. Further, the effect of system performance on optical devices under nonideal conditions is also discussed.

Thirty‐two‐tupling frequency millimeter‐wave generation based on eight Mach–Zehnder modulators connected in parallel

AbstractA new method is proposed to generate a 32‐tupling frequency millimeter wave (MMW) with eight Mach–Zehnder modulators (MZMs) connected in parallel. Theoretical analyses and simulation experiments are conducted. The optical sideband suppression ratio (OSSR) of the obtained ±16th order optical sidebands are 61.54 dB and 61.42 dB, and the radio frequency spurious suppression ratios (RFSSRs) of the generated 32‐tupling frequency MMW are 55.52 dB and 55.27 dB based on the theoretical analysis and simulation experiments, respectively; these outcomes verified the feasibility of the new method. The main parameters used to affect the stability of the generated signal are the modulation index and extinction ratio of MZM. Their effects on the OSSR and RFSSR of the generated signals are investigated when they deviate from their designed values. Compared with the other proposed methods for the generation of 32‐tupling frequency MMW by MZM, our method has the best spectral purity and stability, and it is expected to have important MMW over fiber applications.

RF over fiber system for 5G application

5G communications involve the transfer of several Gb/s information in their small cells. The main solutions for high-speed data transfers for this objective are millimeter-wave RF signals. It is difficult to produce these high-frequency RF signals on the electrical field, so more study is given to the photonic generation of these signals. In this study, the utilization of a dual-drive Mach – Zehnder Modulator (DD-MZM) illustrates a special optical millimeter-wave(MMW) generation. A new method for producing a local oscillator frequency quadrupling optical carrier suppression (OCS) MMW signal utilize two equivalent DD-MZMs based on this form is shown. Data flow on a Radio over Fiber (RoF) network for transmission and generation of a 2.5 Gbps downlink, at OSSR (Optical Sideband Suppression Ratio) of up to 32 dB is acquired by simulation. The Radio Frequency Spurious Suppression Ratio (RFSSRR) is 22 dB

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.

Research on 32-tupling frequency terahertz wave generation based on Mach-Zehnder modulators cascaded

A novel scheme to generate 32-tupling frequency terahertz waves by four Mach-Zehnder modulators (MZMs) cascaded is proposed. Four MZMs are divided into two groups linked in series and each group includes two MZMs connected in parallel. The output of the first group and second group of MZMs are ± 4nth and ± 8nth-order sideband signals, respectively. The 0th-order sideband can be cancelled by adjusting the splitting ratio of coupler; The ± 8th-order sidebands can be suppressed by adjusting the modulation index m of MZMs; The ± 8nth (n＞2) sidebands are negligible because of their very small amplitudes. Then the main components of output signal from the second group MZMs are ± 16th-order sidebands, which can generate 32-tupling frequency terahertz signal on the photodetector. The operation principle and simulation experiment of the proposed scheme is performed, and the optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio (RFSSR) are obtained to be 53.7 dB, 53.34 dB and 47.7 dB, 47.39 dB, respectively. Simulation experiment values are very close to theoretical values and this demonstrates the feasibility of our scheme. The effects on the OSSR and RFSSR deviated from their designed values are investigated. When the deviations of modulation index, extinction ratio, DC bias, half-wave voltage, the insertion loss of MZM reach about ± 0.42 %, 82 %, ± 8.4 %, ± 1 %, 0.14 %, respectively, and when the deviations of initial phase of RF and splitting ratio of coupler reach about ± 1.3 % at 45°, ± 1.1 % at 90°, ± 2.27 %, respectively, the RFSSR are ≥ 15 dB, which satisfies the engineering applications

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 Novel Frequency Double Millimeter Wave Signal Generation Scheme with Optical Carrier Suppression Based on a Single Polarization Modulator

In the work, a novel and simple double frequency millimeter wave (mm-wave) signal generation scheme with optical carrier suppression (OCS) enabled by a single polarization modulator is proposed. The scheme is a simple structure to achieve the mm-wave signal generation, and the core of which just depend on a polarization modulator and two linear polarizers, and electronic circuits is needless to control the drift of modulator bias points and no optical filters is needed to filter out undesirable harmonics. The polarization angle of the first linear polarizer (POL-1) is set to 45°, the polarization angle of the second linear polarizer (POL-2) is set to −45° to suppress even order optical sidebands, and the modulation index of polarization modulator (POLM) is adjusted to realize small signal modulation. Based on mathematical reasoning and computer simulation, the proposed scheme is well feasible. Simulation results show that using 20 GHz RF signal to drive the POLM, 40 GHz mm-wave signal with 47 dB optical sideband suppression ratio (OSSR) and 41.19 dB radio frequency sideband suppression ratio (RFSSR) was obtained.

Generation of a 25-line flattened optical frequency comb and its coherent beating properties.

A 25-line flattened optical frequency comb (OFC) is generated by cascading Mach-Zehnder modulators, and its coherent beating properties are investigated. The effect of bias voltages and the power of radio frequency signals on the flatness of the OFC, and the phase relationships between each comb line are theoretically deduced. In the experiment, a 25-line OFC with a flatness of less than 1 dB and an optical sideband suppression ratio of 12 dB is successfully demonstrated, and the agreement between simulation and experimental results supports the validity of the model for analysis of the flatness. The measured amplitude of harmonic signals by coherent beating of the generated 25-line OFC matches well with the theoretical prediction. A phase noise of -105.31dBc/Hz at 10 kHz frequency offset for the 12th harmonic signal almost without phase noise degradation proves the high coherence of the generated OFC lines.

A Filterless Generation of Optical Millimeter Wave Signal Based on Frequency 16-Tupling Using Cascaded Polarization Modulators

Millimeter wave (MMW) frequencies are becoming vital as they bolster a large number of applications requiring higher data rates. In this paper, we have demonstrated a frequency multiplication technique based on external modulation for a 160 GHz MMW signal generation. The proposed scheme which uses a four-stage cascaded structure of polarization modulators proves to be a lucrative solution since the selected modulation index of 2.826 is phenomenally low. A precise choice of phase shifts between the cascaded stages ensures two eighth-order peaks spaced 160 GHz apart. This technique renders Radio Frequency Spurious Suppression Ratio and Optical Sideband Suppression Ratio of 45 and 65 dB, respectively. Simulation results are verified from a mathematical standpoint. The requirement of a Radio Frequency Local Oscillator with a higher frequency has been eliminated by a higher value of frequency multiplication factor.

Photonic Filter-Free Scheme for D-Band mm-Wave Signal Generation with Frequency 12-Tupling Only via One Integrated In-Phase and Quadrature Modulator

In this work, we have proposed a new scheme of generating continuously tunable and filter-less D-band millimeter-wave (mm-wave) signal with frequency 12-tupling only via one integrated in-phase and quadrature (I/Q) modulator. The two sub-MZMs in the I/Q modulator, biased at peak point, are applied to eliminate odd order optical tones. By controlling the phase and amplitude of RF driving signals, I/Q modulator bias point, and the optical phase shifter embed in the lower arm of I/Q modulator, a frequency 12-tupling signal can be obtained through the beat frequency in the photodetector. Employing 10 GHz RF drive signal, 120 GHz millimeter wave signal can be realized by detailed mathematical formula derivation and simulation, and optical sideband suppression ratio (OSSR) can reach 37.65 dB and radio frequency sideband suppression ratio (RFSSR) can reach 32.08 dB.

Generation of frequency 32-tupling millimeter-wave based on a dual-parallel polarization modulator.

A scheme to generate a frequency 32-tupling millimeter wave (mm-wave) is proposed, enabled by two dual-parallel polarization modulators (DP-PolMs) in cascade. By properly controlling the amplitude and the phase shift of the radio-frequency (RF) driving signal applied to two DP-PolMs, the main optical components at the output of the DP-PolM are ±16th order optical sidebands and the central carrier. After the central carrier is canceled by the polarization multiplexing structure, the ±16th order optical sidebands are beaten in the photodetector; then the frequency 32-tupling mm-wave can be achieved. The optical sideband suppression ratio (OSSR) and the radio-frequency spurious suppression ratio (RFSSR) of the generated signal are 52 and 47 dB in simulation, which are consistent with the theoretical analysis values 53.7 and 47.7 dB. The influence on the OSSR and RFSSR of the generated signal by the key parameters of devices deviating from the theoretical analysis value i are investigated.

A using remodulation filterless scheme of generating frequency 32-tupling millimeter-wave based on two DPMZMs

In this paper, we introduce a filterless system for generating frequency 32-tupling millimeter waves (mm waves) by using two dual-parallel MZMs (DPMZM). A 5 GHz RF signal is used to modulate DPMZM-1. After the first beat, a 20 GHz signal for remodulating DPMZM-2 is generated. Unnecessary sidebands are suppressed by the following methods in the structure of DPMZM-2. Firstly, the ±(4n-2)th-order optical sidebands are suppressed by controlling the phase difference between two Mach-Zehnder modulators (MZMs). Then, the 0th-order sideband is offset by adjusting the value of optical attenuator (OA) and optical phase shifter (OPS). Finally, the 1st and 7th-order optical sidebands nearly disappear by adjusting the modulation index of DPMZM-2 is 3.94. Remaining sidebands enter the photodetector beat frequency to obtain frequency 32-tupling mm waves. Simulation results show that its optical sideband suppression ratio (OSSR) is 27.7 dB and radio frequency sideband suppression ratio (RFSSR) is 27.96 dB, which is consistent with the theory. Using 5 GHz RF signal to drive the DPMZM-1, 160 GHz mm-wave signal was obtained. Furthermore, analyzes the effects of modulation index, optical power and attenuator value on the system performance, optimize the system performance to the best state.

A filterless frequency 32-tupling photonic scheme to generate Sub-Terahertz wave signal enabled by optical polarization modulators

A scheme based on polarization modulators to generate Sub-Terahertz (Sub-THz) wave signal with frequency 32-tupling is proposed. The system consists of two subsystems in cascade, and each subsystem consists of 4 paralleled polarization modulators. In this scheme, by properly controlling two subsystems, an optical signal with optical carrier and ±16th-order optical sidebands is achieved. Next, by adjusting the optical attenuator and optical phase shifter, the optical carrier can be canceled. Finally, the Sub-THz wave with frequency 32-tupling can be obtained after beaten in the photodetector. The results show the ±16th-order optical sideband suppression ratio is 53.38 dB and the radio frequency sideband suppression ratio of the 32-tupling Sub-THz wave is 42 dB, which are consistent with the theoretical analysis very well. Meanwhile, the effects of phase offset, modulation index, and attenuator deviation on suppression ratio are analyzed.

Large Tunable 16-Tupled Millimeter Wave Generation Utilizing Optical Carrier Suppression With a Tunable Sideband Suppression Ratio

Coping up with the rising bandwidth demands for 5G ultra-high speed applications, utilizing millimeter (MM) wave spectrum for data transmission over the radio over a fiber-based system is the ideal approach. In this study, a highly conversant and spectrally pure photonic generation of a 16-tupled MM wave signal using a series-connected DD-MZM with a lower modulation index, a splitting ratio, and a wider tunable range is presented. A 160-GHz MM wave is generated through a double sideband optical carrier suppression technique having an optical sideband suppression ratio (OSSR) of 69 dB and a radio frequency sideband suppression ratio (RSSR) of 40 dB. However, the OSSR and the RSSR are tunable with values greater than 15 dB when the modulation index (M.I.) varies from 2.778 to 2.873, ±8° phase drift, and a 15-dB enhancement in the OSSR with a wider nonideal parameter variation range giving acceptable performance can be seen in the model as compared with previous research works.

Filterless radio-over-fiber system that generates 80 and 160 GHz millimeter waves based on two MZMs.

In this paper, we propose a radio-over-fiber system with no filters and generate 80 and 160 GHz millimeter (mm) waves via two Mach-Zehnder modulators (MZMs). The two MZMs, biased at the maximum transmission point, are used to suppress odd-order sidebands. By controlling the phase difference between the RF driving signal of the two MZMs, the $\pm({4}{n - 2})$-order is canceled. By adjusting the optical attenuator and phase shifter, the 0-order sideband is canceled, so only the $\pm 4{n}$-order sidebands are left. The simulation results show that using a 10 GHz RF signal to drive the MZMs, we obtain an 80 GHz mm wave signal with a 36.59 dB optical sideband suppression ratio (OSSR), a 30.27 dB radio frequency sideband suppression ratio (RFSSR), and a 160 GHz mm wave signal with a 30.34 dB OSSR and 24.77 dB RFSSR. The results are consistent with the theoretical analysis. Because no optical filter is employed and only two MZMs are used, the system exhibits a simple structure, good performance and is low cost.

Photonic Generation and Transmission of 20-Tupling Millimeter-Wave Without Optical Filter

Without the optical filter, a novel approach is designed for frequency 20-tupling photonic millimeter-wave generation based on four nested Mach-zehnder modulators (MZMs). Theoretical derivations and simulation verifications are demonstrated for the millimeter-wave frequency multiplication scheme. Optical sideband suppression ratio (OSSR) of 33 dB and radio frequency sideband suppression ratio (RFSSR) of 28 dB is achieved, respectively. Further, a 1.25 Gb/s data transmission performances are evaluated, the data signal could be transmitted 40 Km with the proposed scheme at BER = 10−9. The obtained results can assist with the design of high frequency radio over fiber (RoF) system.