Optical Millimeter-wave Signal Generation Research Articles

Scheme to eliminate the time shift of code edges based on the optimal transmission point of a DP-MZM.

To eliminate the time shift of code edges on a single-sideband (SSB) modulation signal transmission in a radio-over-fiber (RoF) system, a new, to the best of our knowledge, SSB modulation scheme based on an optimal transmission point for a double-parallel Mach-Zehnder modulator (DP-MZM) is proposed. The scheme is based on DP-MZM to realize the separation of the carrier and the +1st-order sideband at the optimal transmission point, and the baseband signal modulates the 2.5Gb/s data signal to the +1st-order sideband of the SSB signal; then, the carrier and the +1st-order sideband are transmitted with a carrier-to-sideband ratio of 0dB. Theoretical analysis shows that compared to the traditional SSB-modulated optical millimeter-wave signal generation scheme this scheme completely solves the problem of the time shift of code edges caused by dispersion. The simulation results show that the improved SSB modulation scheme has a Q factor of 23.362, the minimum bit error rate is 4.207×10-127 at 73.453km, and the eye diagram is still very clear. Under the premise of meeting the basic requirements of communications, the maximum communications distance can reach 135km, which is 270% of the transmission distance of a traditional SSB modulation model.Thus, the system performance has been greatly improved.

8 phase-shift-keying optical millimeter-wave signal generation by electro-optical phase modulator-based photonic frequency quintupling

We have proposed an 8 phase-shift-keying (PSK) optical millimeter-wave (MMW) signal generation scheme with frequency quintupling enabled by an electro-optical phase modulator (PM) and a wavelength selective switch. In this scheme, the radio frequency (RF) carrier with 8PSK signal is modulated on the lightwave via the PM with simple precoding but constant Euclidean distance, and is recovered to the original 8PSK signal with the frequency-quintupling RF carrier based on the phase periodicity of an 8PSK signal. By optimizing the voltage amplitude of the 8PSK RF driving signal, the generated frequency-quintupled 8PSK MMW signal is maximized at a given laser launch power. A radio over fiber simulation link is built to demonstrate the theoretical analysis. The simulated constellations and bit-error-rate curves show that the frequency-quintupling 8PSK MMW signal has good transmission performance. The simulation results agree well with our theoretical prediction.

All optical Millimeter-wave signal generation and transmission for radio over fiber (RoF) link

<span>Fiber-based wireless system has become a promising solution as a cost- effective communication and it offers high capacity network with millimeter- wave (mm-wave) signal transmission. The system significantly offers superior possible bandwidths for both fiber and free-space applications. Hence, with the increased capacity as well as wireless mobile network applications particularly at mm-wave signal, radio over fiber (RoF) technology is the utmost option. Nevertheless, when high frequency signal transmission is involved, power fading or dispersion effect limits the performance of RoF link. Therefore, this work proposed a RoF system by integrating remote optical local oscillator (LO) with frequency up-conversion at the base station (BS). All optical mm-wave signals are generated and transmitted for the RoF link. The effects of the changes of fiber loop length, optical power of the continuous wave (CW) optical laser carrier and responsivity value of the p-i-n photodiode (PD) mainly at 40 GHz are investigated and the power fading effects are discussed.</span>

Optical millimeter wave generation utilizing stimulated brillouin scattering for radio over fiber system

<span>Optical millimeter-wave signal generation in Radio over Fiber (RoF) based on external modulators using different modulation schemes such as Single-Sideband (SSB), Double-Sideband (DSB) are experimentally compared. The major fallout for external modulation scheme system performance to downgrade is due to dispersion and the fading effect in optical signal generation while generating high Bit Error Rate (BER) when involving long distance delivery. In this work, we proposed mm-wave signal utilize Stimulated Brillouin Scattering (SBS) scheme which indicates the best performance amongst the scheme based on simulation that it achieves to propagate longest of distance over fiber, highest receiver sensitivity, the lowest BER and coherence of Mach-Zehnder Modulator (MZM) extinction ratio. Mm-wave signal of 40 Ghz and 10 Gb/s data rate was generated with the plotting of eye diagram.</span>

Radio-over-fiber system with octuple frequency optical millimeter-wave signal generation using dual-parallel Mach–Zehnder modulator based on four-wave mixing in semiconductor optical amplifier

We have proposed a scheme of radio-over-fiber (RoF) system employing a dual-parallel Mach–Zehnder modulator (DP-MZM) based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). In this scheme, the pump and the signal are generated by properly adjusting the direct current bias, modulation index of the DP-MZM, and the phase difference between the sub-MZMs. Because of the pump and the signal deriving from the same optical wave, the polarization states of the two lightwaves are copolarized. The single-pump FWM is polarization insensitive. After FWM and optical filtering, the optical millimeter-wave with octuple frequency is generated. About 40-GHz RoF system with a 2.5-Gbit / s signal is implemented by numerical simulation; the result shows that it has a good performance after the signal is transmitted over 40-km single-mode fiber. Then, the effects of the SOA’s injection current and the carrier-to-sideband ratio on the system performance are discussed by simulation, and the optimum value for the system is obtained.

Dual-Tone QPSK Optical Millimeter-Wave Signal Generation by Frequency Nonupling the RF Signal Without Phase Precoding

A novel dual-tone quadrature phase-shift keying (QPSK) optical millimeter (mm)-wave signal generation by frequency nonupling the radio-frequency QPSK signal via an optical phase modulator (PM) without phase precoding is proposed. To enable the generated optical mm-wave signal to resist the fiber chromatic dispersion degradation, the unmodulated −fourth-order and the QPSK-modulated +fifth-order sidebands are abstracted from the generated sidebands, considering the phase periodicity of a QPSK signal. The opto-electrical conversion efficiency is maximized by optimizing the modulation index of PM. An optical mm-wave generator along with a radio-over-fiber link is built, and the eye diagrams, constellations, and BER curves demonstrate that the frequency nonupling dual-tone QPSK optical mm-wave signal performs well. The simulated results agree well with the theoretical prediction.

An optical millimeter-wave generation scheme based on two parallel dual-parallel Mach–Zehnder modulators and polarization multiplexing

A novel filterless optical millimeter-wave signal generation scheme is proposed. In the scheme, the undesired sidebands are suppressed using two parallel dual-parallel Mach–Zehnder modulators (MZMs) with different modulation indexes and polarization multiplexing, and frequency multiplication factor as high as 16 can be achieved. Simulation results show that 80, 120, and 160 GHz signals are generated through a 10 GHz RF signal using the proposed method, and the performance of the generated signals is good when commercially available MZMs with extinction ratio of 20–30 dB are used. The scheme has large tunability of modulation index for frequency octupling and 12-tupling signals generation and high stability against the RF driving voltage deviation for frequency 16-tupling generation.

Optical generation of millimeter-wave signals via frequency 16-tupling without an optical filter

Microwave frequency multiplication using two cascaded dual-parallel Mach–Zehnder modulators (DP-MZMs) to generate an optical millimeter-wave (mm-wave) with 16-tupling of the radio frequency (RF) driving signal frequency is proposed. A theoretical analysis leading to the optimum operating conditions including the direct current (dc) bias points, the modulation index, and the phase difference between RF driving signals is developed and demonstrated. A 160GHz mm-wave with an optical sideband suppression ratio (OSSR) of 21.5dB and a radio frequency spurious suppression ratio (RFSSR) of 38dB is generated from a 10GHz RF driving signal, which largely reduce the frequency of electrical driving signal and electrooptic devices. Since no optical filter is employed to suppress the undesired optical sidebands, the system exhibits the advantage of large frequency tunable range.

High-power optical millimeter-wave signal generation with tunable frequency multiplication factor

This work demonstrates a simple and novel scheme for millimeter-wave (MMW) signal generation using optical multi-sidebands (OMSB) modulation. In the proposed methods, several pairs of optical sidebands can be generated by employing parallel phase modulators driven by a low frequency radio frequency (RF) signal. The optical sidebands will beat at a photodetector (PD) to generate high frequency MMW signal with tunable frequency multiplication factor, such as frequency octupling, 12-tupling, 16-tupling and 18-tupling. Since no optical filters or DC bias are used, the MMW signal has the evident character of high-power output. A generalized analytic expression and simulation verification for generating the frequency multi-tupling MMW signal are developed. The influences caused by non-ideal factors are discussed in detail, and undesired power ratios versus non-ideal factors are plotted and analyzed.

A novel optical millimeter-wave signal generation approach to overcome chromatic dispersion

In this paper, a novel frequency octupling approach for optical millimeter-wave signal generation to overcome chromatic dispersion is proposed and demonstrated. The frequency octupling mm-wave with the baseband signal carried only by −4th order sideband is generated by properly adjusting a series of parameters, which are the modulation constant, the gain of baseband signal, the direct current bias and the different phase of the modulation arms. As the optical millimeter-wave signal is transmitted along the fiber, there is no time shift caused by chromatic dispersion. Theoretical analyses and simulated results show that when the optical mm-wave carrying 2.5Gbps baseband signal transmits a distance of over 110km, the eye diagram still keeps open and clear. The power penalty is about 0.4dB after the optical signal transmits over 40km. In additions, given the +4th order sideband carries no data, a full-duplex RoF link based on wavelength reuse is built for the uplink. The bidirectional 2.5Gbps baseband signal could successfully transmit over 40km with about 0.8dB power penalty in the simulation. Both theoretical analyses and simulation results show that the full-duplex RoF link has good performance.

A cost-effective ROF system employing FBG and DML to generate optical mm-wave

We have investigated and experimentally demonstrated a ROF system employing FBG and low-cost DML to generate optical mm-wave. We employ FBG because the bandwidth of the optical modulator is largely reduced and the architecture of the ROF system is simpler. Because no expensive broadband external modulator is used, the overall system is considered as a cost-effective solution. This novel scheme employs low-cost DML to generate mm-wave signal which is a practical scheme to be applied for future broadband access networks. Full Text: PDF References L. Xu and T. Wang, "Key technologies for high-speed digital coherent optical communications", Proc. ICO, pp. 1?2, May, (2011). CrossRef S. Mikel and L. Alayn, "Orthogonally polarized optical single sideband modulation for microwave photonics processing using stimulated Brillouin scattering", Opt. Express, vol. 18, no. 22, pp. 22906?22914, (2010). CrossRef Z. Cao, J. Yu, M. Xia, Q. Tang, Y. Gao, W. Wang, and L. Chen, "Reduction of Intersubcarrier Interference and Frequency-Selective Fading in OFDM-ROF Systems", J. Lightw. Technol., vol. 28, no. 16, 2423?2429, Aug. 15, (2010). CrossRef J. Yu, et al., "Cost-Effective Optical Millimeter Technologies and Field Demonstrations for Very High Throughput Wireless-Over-Fiber Access Systems", J. Lightw. Technol., vol. 28, no. 16, pp. 2376?2397, Aug. 15, (2010). CrossRef C. Tsekrekos, T. Kuri, and K. Kitayama, "Distribution of Millimeter-Wave and Baseband Services Over an Integrated Reconfigurable Access Network Platform", J. Lightw. Technol., vol. 28, no. 19, pp. 2783?2790, Oct. 1, (2010). CrossRef Z. Dong, J. Lu, Y. Pi, X. Lei, L. Chen, and J. Yu, "Optical millimeter-wave signal generation and wavelength reuse for upstream connection in radio-over-fiber systems", Journal of Optical Networking, 7, 736-741, (2008). CrossRef W. Jiang, C. T. Lin, A. Ng'oma, P. T. Shih, J. Chen, M. Sauer, F. Annunziata and S. Chi, "Simple 14-Gb/s Short-Range Radio-Over-Fiber System Employing a Single-Electrode MZM for 60-GHz Wireless Applications", J Lightw Technol., vol.28, no. 16, 2238-2246, (2010). CrossRef J. Ma, "5 Gbit/s Full-Duplex Radio-Over-Fiber Link With Optical Millimeter-Wave Generation by Quadrupling the Frequency of the Electrical RF Carrier", J. Opt. Commun. Netw., vol.3, no. 2, 127-133, (2011). CrossRef Z. Cao, J. Yu, H. Zhou, W. Wang, M. Xia, J. Wang, Q. Tang and L. Chen, "WDM-RoF-PON Architecture for Flexible Wireless and Wire-Line Layout", J. Opt. Commun. Netw., vol. 2, no. 2, 117-121, (2010). CrossRef J. Yu, J. Gu, X. Liu, Z. Jia, G. Chang, "Seamless integration of an 8×2.5 Gb/s WDM-PON and radio-over-fiber using all-optical up-conversion based on Raman-assisted FWM", IEEE Photon. Technol. Lett. 17, 1986-1988, (2005). CrossRef J. Seo, Y. Seo, W. Choi, "1.244-gb/s data distribution in 60-GHz remote optical frequency up-conversion systems", IEEE Photon. Technol. Lett. 18, 1389-1391, (2006). CrossRef J. Yu, Z. Jia, G. Chang, "All-optical mixer based on cross-absorption modulation in electroabsorption modulator", IEEE Photon. Technol. Lett. 18, 2421-2423, (2005). CrossRef H. Song, J. Lee, "Error-free simultaneous all-optical upconversion of WDM radio-over-fiber signals ", IEEE Photon. Technol. Lett. 17, 1731-1733, (2005). CrossRef J. Yu, Z. Jia, L. Yi, Y. Su, G. Chang, "Optical millimeter-wave generation or up-conversion using external modulators", IEEE Photon. Technol. Lett. 18, 265-267, (2006). CrossRef Jianjun Yu, Z. Jia, L. Xu, L.Chen, T. Wang, and G. K, Chang, "DWDM optical millimeter-wave generation for radio-over-fiber using an optical phase modulator and an optical interleaver", IEEE Photon. Technol. Lett. 18, 1418- 1420, (2006). CrossRef M. Attygalle, C. Lim, G. Pendock, A. Nirmalathas and G. Edvell, "Transmission improvement in fiber wireless links using fiber Bragg gratings", IEEE Photon. Technol. Lett. 17, 190- 192, (2005). CrossRef L. Chen, J. He, Y. Li, H. Wen, Y. Shao, C. Huang, L. Hu, Y. Pi, Z. Dong, Y. Li, X. Lei and S. Wen, "Simple ROF configuration to simultaneously realize optical millimeter-wave signal generation and source-free base station operation", ECOC, vol.2, 45-46, (2007) . DirectLink

Optical generation of millimeter-wave and sub-terahertz carrier through frequency 18-tupling

We propose and experimentally demonstrate an optical millimeter-wave and sub-terahertz signal generation method based on frequency 18-tupling using a power amplifier, an optical modulator, and a semiconductor optical amplifier (SOA). The power amplifier is operated in the nonlinear region and generates a third-order harmonic frequency. Next, frequency doubling by optical carrier suppression using the optical modulator is performed. Four-wave mixing of the SOA and optical filtering produce two-tone waves whose frequency spacing corresponds to 18-tupling of the input RF frequency. The experimental results show that two idlers could be obtained at 1549.98 and 1550.85 nm in the wavelength domain corresponding to the beat frequency of 108 GHz from the 6 GHz RF signal. Because of the bandwidth limitations of our available photodetectors, the phase noise of the beat signal is measured at a lower frequency of 60 GHz for the input of 3.3 GHz and is −74.60 dBc/Hz at an offset of 100 kHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1677–1680, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27605

An optical millimeter-wave vector signal generation scheme by frequency quadrupling

This paper demonstrates a novel optical millimeter-wave vector signal generation scheme by frequency quadrupling. Unlike traditional frequency quadrupling modulation schemes, which modulate data on both of the two optical sidebands, and are only suitable for on–off keying modulation format, the proposed scheme modulates the electrical vector signal on the −1st order optical sideband, and generates a pure RF tone on the +3rd order optical sideband. Therefore, frequency quadrupling can be implemented without constellation overlapping after direct detection. A proof of concept simulation experiment is conducted by modulating a 625-Msymbol/s QPSK signal on a 60-GHz RF signal. After transmission over 20-km single-mode fiber, the EVM penalty is negligible.

Optical millimeter-wave signal generation by frequency quadrupling using one dual-drive Mach–Zehnder modulator to overcome chromatic dispersion

We propose a novel approach to generate quadrupling-frequency optical millimeter-wave using a dual-drive Mach–Zehnder modulator (MZM) in radio-over-fiber system. By properly adjusting the phase difference in the two modulation arms of MZM, the direct current (DC) bias, the modulation index and the gain of base-band signal, the quadrupling-frequency optical millimeter-wave with signal only carried by one second-order sideband is generated. As the signal is transmitted along the fiber, there is no time shift of the codes caused by chromatic dispersion. Theoretical analysis and simulation results show that the eye diagram keeps open and clear even when the quadrupling-frequency optical millimeter-wave are transmitted over 110km and the power penalty is about 0.45dB after fiber transmission distance of 60km. Furthermore, due to another second-order sideband carrying no signals, a full duplex radio-over-fiber link based on wavelength reuse is also built to simplify the base station. The bidirectional 2.5Gbit/s data is successfully transmitted over 40km standard single mode fiber with less than 0.6dB power penalty in the simulation.

A filterless optical millimeter-wave generation based on frequency octupling

A novel method of a filterless optical millimeter-wave (MMW) signal generation with frequency octupling using four nested Mach–Zehnder modulators (MZMs) is proposed for Radio-over-fiber systems. By symmetrically biasing the MZMs and using two RF driving signals with 90deg phase delay, a cost-effective, high-quality and filterless optical millimeter-wave at 80GHz with an optical harmonic distortion suppression ratio exceeding 40dB is obtained. The proposed system is insensitive to the MZM bias drift, which demonstrates a relatively higher stability. So it is a viable solution for the future ultra-high frequency MMW applications.

An optical mm-wave generation scheme by frequency octupling using a nested MMI

A novel method of a filterless optical millimeter-wave (MMW) signal generation with frequency octupling via a nested multimode interference (MMI) coupler is proposed for Radio-over-fiber systems. By setting the DC bias voltage applied to the central arms of MMI-b and MMI-c accurately, the optical carrier can be completely suppressed. The OSSR can be as high as about 58 dB without optical filter and the radio frequency spurious suppression ratio (RFSSR) exceeds 32 dB, which is the best result as we know. Simulation results suggest that when the generated optical mm-wave signal is transmitted along the standard single-mode fiber, the eye diagram is still opened after being transmitted over a 50 km fiber.

A frequency sextupling scheme for high-quality optical millimeter-wave signal generation without optical filter

Based on a laser with an integrated Mach-Zehnder modulator (IMZM), a novel frequency sextupling scheme is proposed for the millimeter-wave (mm-wave) signal generation in radio over fiber system. Theoretical analysis is presented to implement the two-tone optical frequency multiplication. The simulation results show that the high-quality frequency sextupling mm-wave signal can be generated without any optical or electrical filter. The optical sideband suppression ratio (OSSR) higher than 29 dB can be obtained without optical filter when the IMZM is consisted of three sub-MZMs with extinction of 30 dB. Furthermore, the influence of imperfect extinction ratio of the IMZM and nonideal phase difference between RF drive signal of two sub-MZMs of the IMZM on OSSR is investigated, and the quality of the generated optical mm-wave signal for two cases of the proposed scheme is also compared.

Multifrequency All-Optical Upconversion Without Cross Talk in a Radio-Over-Fiber System by Using an I/Q Modulator

We propose the multifrequency upconversion of optical millimeter-wave (mm-wave) signal generation by an I/Q modulator. With a 90 deg phase shift, two mm-waves at different frequencies can be easily separated without interference. The receiver power penalty is less than 1 dB for the downlink 40 and 60 GHz mm-wave signals after transmission over 20 km of standard single-mode fiber.

Optical Millimeter-Wave Signal Generation Via Frequency 12-Tupling

This work demonstrates the feasibility of optical millimeter-wave signal generation using frequency 12-tupling. Optical millimeter-wave signal with two sixth-order optical sidebands are generated using frequency quadrupling optical millimeter-wave generation along with optical four-wave-mixing. 210- and 120-GHz two-tone optical signals with optical carrier and undesired harmonic distortion suppression ratios of 20 and 30 dB are experimentally demonstrated. The proposed system provides an attractive method for millimeter-wave applications such as optical up-conversion in radio-over-fiber (RoF) communication systems at millimeter-wave band, phase-array antennas, optical sensors, radars, and tera-hertz applications.

A continuously tunable and filterless optical millimeter-wave generation via frequency octupling

This work proposes a cost-effective, continuously tunable and filterless optical millimeter-wave (MMW) signal generation employing frequency octupling. Optical MMW signals with 30-dB undesired sideband suppression ratios can be obtained. Since no optical filtering is required, the proposed system can be readily implemented in wavelength-division-multiplexing (WDM) systems. V-band 60-GHz and W-band 80-GHz optical MMW signals are experimentally demonstrated. Because of the high undesired sideband suppression ratio, 60-GHz waveform with 50% duty cycle is observed. The single-sideband (SSB) phase noise of the generated 60-GHz signal is -73 dBc/Hz at 10 kHz. The proposed system is a viable solution for the future ultra-high frequency MMW applications up to 320 GHz using the external modulator with a limited bandwidth of 40 GHz.