Chenhui Ye

Generation and transmission of multiband and multi-gigabit 60-GHz MMW signals in an RoF system with frequency quintupling technique.

We propose and experimentally demonstrate a cost-effective radio-over-fiber (RoF) system to simultaneously generate and transmit multiband and multi-gigabit 60-GHz millimeter wave (MMW) signals using frequency quintupling technique. Multiband signals at 56-GHz and 60-GHz are realized with two cascaded single-drive Mach-Zehnder modulators (MZMs), where phase control is not required. Furthermore, only low-frequency (≤12GHz) optical and electrical devices are used in the central station (CS), which enable a cost-effective system. At the user-terminal, two-stage down-conversions are employed by envelope detection (ED) and intermediate frequency (IF) mixing, eliminating expensive high-speed synthesizer and critical phase control components. Error-free performances are achieved for the multiband MMW signals after 50-km single-mode fiber (SMF) and 10-ft wireless link transmissions.

A Bidirectional 60-GHz Wireless-Over-Fiber Transport System With Centralized Local Oscillator Service Delivered to Mobile Terminals and Base Stations

We propose a novel 60-GHz wireless-over-fiber (WoF) access system for multigigabit bidirectional data transmission. In conventional microwave wireless system designs, electrical local oscillator (LO) sources are required for frequency conversions in both base station (BS) and mobile terminal (MT), incurring considerable cost for system integration and maintenance at millimeter-wave frequencies. We design a WoF transport system, aiming to centralize system functions in the central office (CO), without requiring electrical LO devices in both BS and MT. In our proposed scheme, LO has been centralized in CO, the LO signal is distributed as a service to carry out frequency up-/down-conversion functions required in BS and MT. Thus, in this simplified system architecture, the overall cost can be reduced and the operation quality of centralized LO service enhanced. The operation principle and feasibility of error-free transmission of multigigabit, bidirectional data streams over both fiber and free space has been demonstrated experimentally.

Generation of Multiband Signals in a Bidirectional Wireless Over Fiber System With High Scalability Using Heterodyne Mixing Technique

We propose and experimentally demonstrate a bidirectional radio over fiber system to simultaneously generate and transmit downstream multiband signals and upstream data. To the best of our knowledge, this is the first time that the multiband signals, including baseband, 24-GHz microwave (MW), and 42- and 60-GHz millimeter-wave (MMW) signals, are realized through multicarrier generation and heterodyne mixing techniques. The frequencies of the MW and MMW signals are continuously tunable, thus high scalability can be achieved. In the base station, part of the continuous wave light is used as an optical carrier for upstream data, which is transmitted back to the central station though the same fiber. Error-free performances are achieved for all the signals after 25-km single-mode fiber and 5 ft air link transmission for wireless data.

All-Optical Approach to Microwave Frequency Measurement With Large Spectral Range and High Accuracy

An all-optical approach for microwave frequency (MWF) measurement with a low-speed oscilloscope is proposed and experimentally demonstrated. In this scheme, an optical Alter with a single and ultranarrow passband, together with a tunable laser and a low-speed photodiode is utilized to calculate the MWF by measuring the time delay between the sweeping optical carrier and its upper/lower sideband passing through the filter. Single-frequency and multifrequency measurements are experimentally demonstrated. The measurement recognition, accuracy, and resolution are below 0.1, 0.09, and 0.2 GHz, respectively. This proposed scheme can be easily upgraded to higher frequencies using a modulator with higher bandwidth proportional to the desired measurement range.

All-Optical Transversal Filter With Tap Increasing and Negative Coefficients Based on Double-Pass Modulation

A novel microwave photonic filter with tap increasing and negative coefficients is proposed and experimentally demonstrated. The negative coefficient is achieved by employing a phase modulator, while the tap increasing is based on double-pass modulation of a Mach-Zehnder modulator (MZM). The experimental results demonstrated that stable five-tap bandpass filter characteristics can be obtained by using only one optical source. The experimental results of the proposed filters also show tunability and partial reconfigurability.

Millimeter-Wave Harmonic Signal Generation and Distribution Using a Tunable Single-Resonance Microwave Photonic Filter

A millimeter-wave (mm-wave) harmonic signal generation method is proposed and verified experimentally. The mm-wave harmonic signals of high order are generated through the intrinsic nonlinear transfer characteristics of the Mach-Zehnder amplitude modulator. A tunable single-resonance microwave photonic filter is used to select the specific order of harmonic signal. Signals up to the fourth harmonic at 20 GHz can be generated by low-frequency driving signal at 5 GHz.

An All-Optical Transformer From Differential NRZ Data to Ultra-Wideband Pulse Stream

We propose and experimentally demonstrate a compact and cost-effective scheme based on a fiber Sagnac structure to realize real time conversion from differential nonreturn-to-zero (NRZ) data to ultra-wideband (UWB) pulse stream. The proposed conversion system for the UWB signal generation consists of a single-wavelength laser, a phase modulator, several polarization controllers, and optical couplers. Due to the optical interference between the two phase-modulated light waves with slight phase difference in the Sagnac loop, two sharp optical pulses with opposite polarities are obtained. With proper time delay, a UWB monocycle pulse stream is generated from the original differential NRZ data. Our proposed method gives a reliable, easy, and low-cost transformer from differential NRZ signal to UWB pulse stream, and no high-speed arbitrary waveform generator (AWG) is required in this all-optical transformer.

A bidirectional multi-band 60-GHz wireless-over-fiber transmission system with compacted base station and mobile terminal using a robust mm-Wave LO free technique

For the first time, bidirectional multi-band multi-gigabit wireless-over-fiber transmission at 60-GHz mm-wave band has been accomplished with centrally supplied LO service. It does not require mm-wave LO devices in each base stations and mobile terminals.

Multi-service, multi-band, and MIMO data distribution over 60-GHz RoF system for gigabit wireless local area networks

We propose and experimentally demonstrate a 60-GHz RoF system to support 3M (multi-service, multiband and MIMO) data distribution. Spectral efficiency is improved and system capacity is doubled by using 2×2 MIMO spatial multiplexing.

Duobinary RF envelope detection in coherent optical millimeter-wave systems

A novel duobinary RF receiver is proposed and demonstrated based on RF envelope detection for millimeter-wave radio-over-fiber systems. Robust RF downconvertion and duobinary decoding are achieved simultaneously at an RF envelope detector. Duobinary signal delivery over wired and wireless link in coherent single-sideband optical millimeter-wave systems is demonstrated for the first time.