A photonic generation of microwave frequency shift keying signal (FSK) with large frequency tunability is proposed and experimentally demonstrated. A polarization modulator combined with a polarization maintaining fiber Bragg grating is used to transform a carrier-suppressed double sideband signal to a wavelength-shift-keying one, which is subsequently mixed with a tunable optical source to achieve frequency modulation. A proof-of-concept experiment is demonstrated to obtain an FSK signal at 9.5/12.5 GHz. The carrier frequency has been tuned from 7.2 to 14.8 GHz by adjusting the laser wavelength. Moreover, a radio over fiber transmission link is established to investigate the transmission performance of the generated FSK signal. The bit-error-rate curve of the received FSK signal at 9.5/12.5 GHz for a 5-km single mode fiber and 2-m wireless transmission is presented.

Photonic Generation of Microwave Frequency Shift Keying Signal Using a Polarization Maintaining FBG

A photonic scheme to generate a 4-level frequency hopping (FH) microwave signal is proposed and experimentally demonstrated. The frequency of the generated signal can be fast and flexibly switched by shifting the combinations of two binary signals (i.e., 00, 01, 11, 10). Moreover, the carrier frequencies of the signal can be tuned in a large range. In the experiments, 2/4/6/12, 4/6/8/12, and 6/9/12/18 GHz FH signals are generated with the FH speed up to gigahertz.

Photonic Generation of Multilevel Frequency-Hopping Microwave Signal

Multiband microwave photonic filters (MPFs) are extensively required in emerging multifunction RF systems and high-performance radar systems. In this article, we present a reconfigurable and tunable multiband MPF. The flexible amplitude and phase controls of the multiband MPF can be achieved via optical spectral slicing by way of a programmable sampling function, i.e., varying the number of samples or the duty cycle of each sample. We verify that the number of uniform passbands can be adjusted (we obtain up to six passbands) and demonstrate a frequency tuning range of up to 432 MHz for a uniform triple-passband MPF. We also show a highly chirped triple-passband MPF with respective in-band chirps up to 30.0 ns/GHz, 42.1 ns/GHz, and 22.8 ns/GHz. These latter results illustrate a potential way to implement highly chirped multiband MPFs for high bandwidth signal processing applications.

Optical Spectral Slicing Based Reconfigurable and Tunable Microwave Photonic Filter

A novel scheme of microwave photonic generation of binary digitally modulated signals is proposed and experimentally demonstrated, which can simultaneously generate 2ASK, 2PSK and 2FSK. By dynamically manipulating an optical frequency comb, different modulation formats can be switched. Moreover, the bit rate and carrier frequency of the generated RF signals can be tuned.

Photonic generation of RF binary digitally modulated signals.

Photonic generation of microwave binary digital modulation signal with format agility and parameter tunability

A novel approach to generating microwave frequency shift keying (FSK) signals using a polarization modulator (PolM) and a dual-polarization Mach–Zehnder modulator (DPol-MZM) is proposed and experimentally demonstrated. In the proposed system, the PolM is employed to modulate the polarization state of an input linearly polarized lightwave to switch between two orthogonal directions, leading to the generation of a polarization shift keying (PolSK) signal. Then the PolSK signal is sent to a DPol-MZM, which is made up of two polarization multiplexed sub-MZMs by a polarization controller (PC). Two microwave signals with different frequencies are applied to the sub-MZMs. After aligning the orthogonal directions of the PolSK signal with the axes of the DPol-MZM by the PC, the PolSK signal can be converted into a microwave FSK signal. A proof-of-concept experiment is carried out to verify the proposed system. When the sub-MZMs in the DPol-MZM are biased at a quadrature point, a double sideband microwave FSK signal at 3/6.5 GHz with a bit rate of 1.25 Gb/s is generated and transmitted over 10 km of single-mode fiber. When the sub-MZMs are biased at minimum point, an optical carrier suppression microwave FSK is achieved at frequency-doubled 6/14 GHz with a bit rate of 2.5 Gb/s.

Photonic Generation of Microwave Frequency Shift Keying Signals

This paper proposes a tunable multiple-passband microwave photonic filter (MPF) that is incorporated with an injection-locked Fabry-Perot (FP) laser. In the proposed MPF, multiple passbands can be easily generated based on the frequency-selection effects of the laser structure in the case of multiple light waves injection. The novelty here is that the obtained multiple-passband MPF can achieve either a dual-passband or a single-passband by using merely one experimental scheme. Moreover, since the laser injection ratio of the proposed scheme is high, the central frequency of each passband has a large tunable range. More tunable passbands can be generated by employing more external wavelengths. By fine-detuning the injection parameters, the frequency tuning range of 17 GHz and the out-of-band rejection ratio of 24.1 dB are achieved for the dual-passband MPF, and the out-of-band rejection ratio of 22 dB and the 3-dB bandwidth of 360 MHz are achieved for the single-passband MPF. In addition, the attained peak power and bandwidth of the proposed MPF are investigated with respect to the injection parameters, including detuning frequency, injection ratio and bias current of FP laser. The stability and dynamic range of the MPF are also evaluated through experiments.

Tunable multiple-passband microwave photonic filter based on external optical injected Fabry-Pérot laser.

We propose all-optical signal upconversion scheme using optically-injected DFB in combine with embedded optoelectronics oscillator for RoF application. The low-noise LO provided by OEO and near-SSB modulation implemented by injection locking enables high-performance in transmission.

All-optical signal upconversion using optically-injected DFB laser and embedded optoelectronic oscillator for radio-over-fiber applications

A new method of microwave photonic filter (MPF) with widely tunable passband is proposed and experimentally proved by using an optical-injected Fabry-Perot laser diode. It is based on the basic principle that the FP laser wavelength selectively amplified under optical injection. By applying the optical wave from a tunable-laser source (TLS) to the PM, a phase modulated optical signal is generated, which injects to the slave laser by the circulator. The overall procedure substantially corresponds to a single passband MPF with its central frequency of the passband by changing the injection locking parameters of the TLS. The proposed MPF has been evaluated experimentally. It is achieved that the single passband MPF with a frequency adjustable range of 23 GHz and a bandwidth of 275 MHz. The out of band suppression ratios or insertion loss is 27.9 dB. These are very useful in many places that require wideband tunablity and high frequency.

Narrowband widely tunable single passband microwave photonic filter using optical-injection of a Fabry-Perot laser diode

An all-optical signal up-conversion scheme using a directly modulated DFB semiconductor laser and an optoelectronic oscillator is proposed and experimentally demonstrated. By directly modulating a DFB semiconductor laser, a higher modulation efficiency and a lower conversion loss are achieved comparing with the modulators based schemes. The 40 Mb/s 16QAM signal working at 1 GHz is successfully up-converted to 10.68 GHz. The conversion loss is independent of the frequency and the power of the intermediate-frequency signal.

Ji Tao

Papers

Photonic Generation of Microwave Frequency Shift Keying Signals

Tunable multiple-passband microwave photonic filter based on external optical injected Fabry-Pérot laser.

All-optical signal upconversion using optically-injected DFB laser and embedded optoelectronic oscillator for radio-over-fiber applications

Narrowband widely tunable single passband microwave photonic filter using optical-injection of a Fabry-Perot laser diode

All-optical signal up-conversion based on a directly modulated DFB semiconductor laser and an optoelectronic oscillator