Optical Millimeter-wave Generation Research Articles

Multiband 60-GHz Wireless Over Fiber Access System With High Dispersion Tolerance Using Frequency Tripling Technique

A new optical millimeter-wave generation scheme to triple the beating frequency based on subcarrier multiplexing in combination with single sideband technique is proposed, capable of high tolerance of fiber chromatic dispersion. The proposed scheme can be applied to two types of multiband 60-GHz wireless over fiber access systems: one with widely separated bands including millimeter-wave, microwave and baseband and the other one with multiple 60-GHz sub-bands. Experimental verification of the proposed system with widely separated bands is presented with the generation and error-free transmission of 2.1-Gb/s data on the 63-GHz mm-wave and 21-GHz microwave carriers over 50-km single-mode fiber (SMF-28) without dispersion compensation. The power penalties caused by 50-km fiber transmission for both signals are both less than 1.0 dB at BER of 10-9 Meanwhile, simultaneous generation and transmission of multiple services at 60-GHz sub-bands are also introduced. The experimental results demonstrate the successful delivery of the 1-Gbps data carried by 60-GHz millimeter-wave both over 50-km SMF-28 and wireless distance of 6-m without any dispersion compensation. The optical receiver sensitivity of the transmission with two sub-bands degrades by 2 dB compared with the single band 60-GHz signal, and the power penalty from 50-km SMF-28 transmission is 0.8 dB at BER of 10-9. From the theoretical analysis and experimental demonstrations of the two multiband systems, it is concluded that the proposed millimeter-wave generation scheme indeed increase the transmission distance for the system with 60-GHz signal, which normally having SMF transmission distance of few tens of kilometers, by utilizing optical and electrical components with low-bandwidth requirements.

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.

Using dual-mode self-locked semiconductor laser for optical millimeter-wave application

In this study, an optical millimeter-wave (mm-wave) generator is proposed and experimentally demonstrated by using a self-injected Fabry-Perot laser diode (FP-LD), having mode spacing of 1.11 nm, for dual-mode beating in 140 GHz band (terahertz band). The created dual-wavelength also can be also modulated at 1.25, 2.5, and 10 Gb/s with on-off keying (OOK) modulation format by external optical modulator, respectively, in 20 km fiber transmission. Moreover, the dual-mode laser can be selected in difference wave-lengths by tuning the optical filter inside cavity for the future WDM applications.

5 Gbit/s Full-Duplex Radio-Over-Fiber Link With Optical Millimeter-Wave Generation by Quadrupling the Frequency of the Electrical RF Carrier

A scheme to implement the full-duplex radio-over-fiber (RoF) link by quadrupling the frequency of the electrical RF carrier without a lightwave source at the remote base station (RBS) is proposed. Not only does the scheme reduce the complexity of the RBS and its frequency requirement for the devices, but the generated optical millimeter-wave (mm-wave) signal also has good transmission performance because both the fading effect and the bit walk-off effect caused by fiber dispersion are avoided. A 5 Gbit/s full duplex RoF simulation link with a 40 GHz optical mm-wave signal is built. It shows that the eye diagrams of both the uplink and downlink signals remain open and clear even after the signals are transmitted over 60 km standard single-mode fibers. The simulation results agree well with our theoretical prediction.

Optical Generation of Modulated Millimeter Waves Based on a Gain-Switched Laser

We propose and demonstrate two configurations for optical millimeter-wave (mm-wave) generation and transmission of 3-Gb/s downstream data based on a gain-switched laser (GSL). The first configuration generates an optical comb spectrum from a GSL that can be appropriately filtered to generate two optical sidebands with 60-GHz separation. These sidebands are modulated with baseband data by using an external intensity modulator and then transmitted via optical fiber to the remote antenna unit (RAU). The second configuration produces a modulated optical frequency comb by driving the laser with both RF local oscillator and data streams coupled together and then followed by the same optical filters to generate two modulated optical sidebands. At the RAU, these two sidebands are heterodyned using a photodetector to generate the electrical modulated mm-wave signal. We investigate the distribution of these two methods over 3-km fiber with 2-m wireless link and demonstrate the system simplicity and cost efficiency for mm-wave over fiber systems. Both configurations are simulated to verify our obtained results and show system performance at higher bit rates.

Optical Millimeter-Wave Generation and Transmission Without Carrier Suppression for Single- and Multi-Band Wireless Over Fiber Applications

A new optical millimeter-wave generation scheme to double the beating frequency without suppressing the carrier by taking advantages of the out-of-phase property between sidebands of a phase-modulated optical carrier is proposed for the first time. Theoretical analysis shows that the generated 60 GHz optical millimeter-wave (mm-wave) can tolerant ±0.016 nm wavelength drifting with filter bandwidth ranging from 70 to 100 GHz to sustain first to second harmonic suppression ratio of 18 dB. The doubled frequency is continuously tunable from 60 to 90 GHz within 100 GHz filter bandwidth with RF power variation of less than 2 dB. In addition, simultaneously generating and transmitting multi-band signal: millimeter-wave band, microwave band, and baseband leveraging the same concept is also proposed. Error-free transmission of 2.5 Gb/s wireless baseband signals carried by the generated 60 GHz mm-wave is successfully demonstrated in both single- and multi-band network environments over a combined optical fiber and wireless distance with a proper equivalent isotropically radiated power of about 20 dBm for in-building access. Moreover, dispersion effect on the generated frequency-doubled optical mm-wave is analyzed by experimentally comparing the link performance of both single mode fiber (SMF-28) and dispersion-shifted fiber cases. It is concluded that for single-band service delivery, the proposed scheme is immune to the interference from the dispersion-induced, redundant 1st harmonics; however, to deliver multi-band services, launching lightwave at zero-dispersion wavelength over SMF-28 is highly recommended to mitigate inter-band interference.

Flexible V‐band optical millimeter‐wave carrier generation techniques using optical injection locked Fabry‐Pérot laser diodes

AbstractNovel schemes, for V‐band (60‐GHz frequency range) optical millimeter‐wave (mm‐wave) carrier generation in radio‐over‐fiber system, are proposed and experimentally demonstrated that are based on injection‐locked Fabry‐Pérot laser diodes.Dual‐parallel and cascaded structures are individually proposed to generate the mm‐wave carrier. We could improve the suppression ratio (SR) of the carrier suppressed optical signal as well as reduce RF phase noise of the mm‐wave carrier by using the proposed schemes. The SR improvement of the carrier suppressed optical signal of 20 dB was verified. 60‐GHz mm‐wave carrier of enhanced signal quality could be also achieved. Its peak power and RF phase noise were obtained as about −40 dBm and less than −95 dBm, respectively, which was suitable for 60‐GHz data transmission. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1685–1691, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25322

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.

On Frequency-Doubled Optical Millimeter-Wave Generation Technique Without Carrier Suppression for In-Building Wireless Over Fiber Applications

A novel optical millimeter-wave (mm-wave) generation scheme based on double-sideband phase modulation (DSB-PM) to achieve frequency doubling without suppressing the carrier is proposed. Theoretical analysis shows that the generated 60-GHz optical mm-wave can tolerant ± 0.016-nm wavelength drifting with filter bandwidth ranging from 70 to 100 GHz to sustain first to second harmonic suppression ratio of 18 dB. In addition, error-free transmission of 60-GHz mm-wave at 2.5 Gb/s is experimentally demonstrated over a combined distance of 3-m wireless with 21-dBm equivalent isotropically radiated power, and 250-m fiber to best emulate an in-building network environment. Dispersion effect on the frequency-doubled PM optical mm-wave without carrier suppression is also analyzed and experimentally studied by comparing the link performance over single-mode fiber (SMF-28) and dispersion-shifted fiber (DSF), respectively.

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.

基于相位调制器产生六倍频光毫米波的OFDM信号光传输系统研究

A full-duplex radio-over-fiber system with sextuple optical millimeter-wave generation transmit OFDM signal utilizing two parallel phase modulators is proposed.2.5 Gbit/s OFDM signal is modulated on the optical millimeter wave with 60 GHz frequency and transmitted to the base station over standard single-mode fiber(SMF).The generation principle and the transmission performance over fiber of optical millimeter wave generation are analyzed by theory and simulation,respectively.The results show that OFDM have more advantage than NRZ in ROF system.

采用级联相位调制器和强度调制器产生四倍频光载毫米波的光纤无线通信系统

采用级联相位调制器和强度调制器产生四倍频光载毫米波的光纤无线通信系统

Simplified optical millimeter-wave generation configuration by frequency quadrupling using two cascaded Mach–Zehnder modulators

We propose what we believe to be a novel method to generate optical millimeter-wave signals with frequency quadrupling using two cascaded Mach-Zehnder modulators (MZMs). Both theoretical analysis and experimental demonstration are presented. By symmetrically biasing the MZMs, without any optical filters or electrical devices, a high-quality millimeter wave at 40 GHz with an optical harmonic distortion suppression ratio of more than 25 dB is obtained. Furthermore, it is also proved to be valid that the proposed scheme is insensitive to the MZM bias drift, which demonstrates a relatively higher stability.

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.

Optical millimeter-wave generation and transmission system for 1.25Gbit/s downstream link using a gain switched laser

In this paper, we propose a novel and cost effective system for optical millimeter-wave (mm-wave) generation and transmission of downstream data based on a gain switched laser (GSL). The GSL produces an optical comb spectrum that can be appropriately filtered to generate two optical sidebands spaced by more than 4 times the repetition rate of the GSL. These sidebands are modulated by baseband data and then transmitted via optical fiber to the remote antenna unit (RAU). At the RAU, the two sidebands are heterodyned using a photodetector to generate the electrical modulated mm-wave signal, before demodulation using self mixing. We demonstrate the distribution of 1.25 Gbit/s data OOK modulated onto a 60 GHz carrier, similar to that used in the IEEE 802.15.3c draft standard, over fiber lengths up to 62 km.

Full-duplex radio-over-fiber system with photonics frequency quadruples for optical millimeter-wave generation

We have experimentally investigated two different schemes (schemes A and B) to generate optical millimeter-wave using optical frequency quadrupling with a Mach–Zehnder modulator (MZM), and wavelength reuse for uplink connection in the radio-over-fiber (ROF) systems. For scheme A, only one MZM is used for both the optical millimeter-wave generation and signal modulation. For scheme B, two MZMs are used. In this scheme, one of MZMs is used to generate optical millimeter-wave for frequency quadrupling, and another one is used for signal modulation. In both schemes, at the base station (BS), the optical carrier can be reused to carry upstream data and delivered to the central station (CS). By experimentally comparing the performance of downstream and upstream transmission in two schemes, it can be seen that scheme B can overcome the crosstalk between the upstream and downstream signals, but scheme A cannot. Meanwhile we also show that the millimeter-wave generated in scheme B has better quality and is almost robust to fiber chromatic dispersion.

Optical millimeter-wave signal generation and wavelength reuse for upstream connection in radio-over-fiber systems

We theoretically and experimentally investigate three different schemes to generate optical millimeter-wave and wavelength reuse for uplink connection in radio-over-fiber (ROF) systems. In these schemes, the optical millimeter waves (mm-waves) are generated via a LiNbO3 Mach-Zehnder modulator with the double-sidebands scheme. Particularly, we experimentally demonstrate what we believe to be a new scheme (scheme III) to genetate optical mm-waves by a multiple double-frequency technique to further reduce the overall cost. We compare the performance of the three different schemes for ROF systems considering the cost and configuration of their architectures.

Full-Duplex 1.0 Gbit/s Data Transmission Over 60 GHz Radio-on-Fiber Access System Based on the Loop-Back Optical Heterodyne Technique

Full-duplex transmission over a 60 GHz radio-on-fiber access system based on the optical heterodyne technique is verified in this paper. With this technique, an optical carrier generator on the transmitting side consolidates the functions of wavelength and polarization control for optical heterodyne detection in uplinks and optical millimeter-wave generation in downlinks, on behalf of each optical transmitter/receiver. Therefore, the whole system configuration can be significantly simplified. A full-duplex 1.0 Gbit/s transmission experiment over 10 km of single-mode fiber, which represents an access network transmission, is demonstrated using the simultaneous modulation/photodetection operation of an electroabsorption modulator (EAM). Bit error rates of less than 10-9 were obtained in both the uplink and downlink without noticeable mutual interference, even though the laser source and the EAM is shared by both links, and no significant dispersion-induced degradation was observed. Moreover, the experimental results showed that an optical link budget of 9.2 dB can be achieved with the experimental configuration.

Centralized lightwave radio-over-fiber system using only one phase modulator for optical millimeter-wave generation

We propose and demonstrate a novel radio-over-fiber (ROF) architecture by using only one phase modulator and one optical filter to generate an optical millimeter (mm) signal and realize wavelength reuse for upstream data connection. In the central office, the rf signals are generated by an electrical mixer that mixes the local oscillator (LO) and downstream data, and a phase modulator is used to generate an optical millimeter-wave signal. In the base station, an optical interleaver with two output ports is used to separate the optical carrier and the first-order sidebands. The separated first-order sidebands are used to generate optical millimeter-wave signals with a double LO frequency, while the separated optical carrier is reused for an uplink connection. There is no additional laser source for the upstream data generation in the base station and no dc-bias controller for phase modulator. By this method, we simplify the configuration of the radio-over-fiber system and reduce the cost of the system.

A full-duplex radio-over-fiber system using direct modulation laser to generate optical millimeter-wave and wavelength reuse for uplink connection

In this paper, we present a full-duplex radio-over-fiber system incorporating both optical millimeter-wave (mm-wave) generation and wavelength reuse for uplink connection. The optical double sidebands (DSB) signal is generated by using only one inexpensive broadband direct modulation laser (DML), to which a mixing RF signal is applied. An optical interleaver is then used to separate the first-order optical sidebands from the optical carrier of optical DSB signal. The separated first-order optical sidebands are beat to generate mm-wave signal that has double the frequency of the RF drive signal, while the separated optical carrier is reused as light source to remodulate uplink signal. Both detailed theoretical analysis and experiments to demonstrate the feasibility of the proposed system are presented. Experiment result shows that the bidirectional 2.5Gb/s data can be successfully transmitted over 40km standard single-mode fiber (SSMF) with less than 2dB power penalty.