Tianliang Wang

A Photonic Microwave Frequency Quadrupler Using Two Cascaded Intensity Modulators With Repetitious Optical Carrier Suppression

We theoretically analyzed and experimentally demonstrated a novel 4- to 40-GHz frequency quadrupler for radio-over- fiber systems. By using an optical carrier suppression modulation scheme in two cascaded intensity modulators, four-fold microwave or millimeter wave signals are optically generated without the need for an optical and electrical notch filter to remove the residual carrier components. Moreover, the limitation of high drive voltage is greatly reduced through tandem intensity modulation with pi/2 phase shift between two driving signals.

Methods for Ultra-Wideband Pulse Generation Based on Optical Cross-Polarization Modulation

Optical methods for different type ultra-wideband (UWB) pulse generation based on cross-polarization modulation (CPM) are proposed and demonstrated in this paper. Two polarity-reverse pulses can be obtained by CPM and birefringence time delay to form a monocycle pulse. A semiconductor optical amplifier (SOA) is placed after the monocycle pulse process for doublet pulse generation. These two kinds of pulses can be employed in single-band impulse radio UWB (IR-UWB) systems. Two kinds of multi-band UWB pulses can be generated based on monocycle pulse train with proper apodization profiles, realized by hybrid photonic microwave filter and synchronous polarization modulation respectively. Experimental results show that these pulses can be used in multi-band UWB (MB-UWB) over fiber systems.

Photonic generation of a millimeter-wave signal based on sextuple-frequency multiplication.

A millimeter-wave signal with sextuple-frequency multiplication of a microwave source is obtained with two cascaded optical modulators, which are driven by the same microwave source with phase deviation of pi/2 introduced by an electrical phase shifter. Without any optical filter, a wideband continuously tunable millimeter-wave signal is easily generated.

Millimeter-Wave Signal Generation Using Two Cascaded Optical Modulators and FWM Effect in Semiconductor Optical Amplifier

A novel method of optical generation millimeter-wave (mm-wave) signals employing two cascaded optical modulators and four-wave-mixing effect in semiconductor optical amplifiers is proposed. This approach is capable of generating signals of four times, eight times, and 12 times microwave source frequency with high spectral purity and stability. A mm-wave of 42 GHz (12times fundamental) with a 3-dB linewidth less than 30 Hz and a phase noise less than 83 dBc/Hz at 10-kHz offset is obtained.

High-Spectral-Purity Millimeter-Wave Signal Optical Generation

In this paper, novel approaches for millimeter-wave signal generation using double-sideband suppressed-carrier modulation and four-wave mixing are proposed and demonstrated. The millimeter-wave signal is generated at a photodetector by beating the optical sidebands, which are gained from intensity modulation and after semiconductor optical amplifiers. In the proposed methods, the generated millimeter-wave signal has a frequency that is double, quadruple, sextuple, 12 times, or even 18 times higher than the microwave drive signal. And, it has quite good gain flatness with extremely high-spectral-purity and stability. The phase noise performance of the generated millimeter wave is investigated. The 3-dB linewidth of the millimeter wave has no broadening after propagating through 20-km standard single-mode fiber.

Millimeter-Wave Signal Generation Using Four-Wave Mixing Effect in SOA

Optical generation millimeter-wave signals employing FWM effect in SOA is proposed. Sextuple fundamental frequency millimeter-wave of 42GHz with 3dB linewidth 20Hz and phase noise less than -75dBc/Hz at 1.6 kHz offset is obtained.

All-optical up-conversion for 2.5-Gb/s signals in ROF systems based on FWM effect in HNLF

We propose and demonstrate experimentally a novel scheme to realize all-optical up-conversion and wavelength-conversion based on the bi-directional-pump four-wave mixing (FWM) effect in high nonlinear fibers (HNLFs). The pump is generated with optical carrier suppression in a Mach-Zehnder modulator. The two pumps are always parallel and phase-locked. A balance-detection photo-detector for optical signal detection is employed with 3-dB improvement in power penalty. The 2.5-Gb/s signals are transmitted successfully over the 25-km single-mode fiber in 30-GHz radio over fiber (ROF) systems.

A simple approach of high-purity millimeter-wave signal photonic generation

A simple method of optical generation millimeter-wave signal employing optical phase modulator and band-elimination filter is proposed. This simple approach is capable generate millimeter wave signal of quadrupled or sextuple microwave source frequency with extremely high spectral purity. Millimeter-wave signal 26GHz (quadrupled fundamental frequency) or 39 GHz (sextuple fundamental frequency) is obtained respectively using different system chromatic dispersion when the microwave driver signal is at 6.5GHz.

Key technologies and system design for various radio over fiber applications

Abstract Key technologies and new system designs for various radio over fiber (RoF) applications are proposed and demonstrated. For ultrawideband (UWB) over fiber applications, several UWB pulses generation and distribution methods are carried out. Different kinds of UWB pulses are generated based on cross-polarization modulation methods. For millimeter-wave (mm-wave) wireless applications, a 32 GHz RoF system is demonstrated with microwave frequency sextupling by optical methods. After 20 km SMF transmission, the power penalty of 2.5 Gbit/s downlink service is less than 0.15 dB. It is also suitable to apply dense wavelength division multiplexing (DWDM) technology to RoF system to support numerous base stations (BSs).

A novel mode-locked laser based on SOA and optical feedback

Optical trains with repetition rates as high as 10GHz~40GHz are obtained by using a novel high speed mode-locked fibre laser. It combines both active mode-locked effect and passive mode-locked effect so the FWHM of the output optical pulses can be decreased to 2ps. And the performance of the proposed fiber laser is analysed.