Ninghua Zhu

A Frequency-Doubling Optoelectronic Oscillator Based on a Dual-Parallel Mach–Zehnder Modulator and a Chirped Fiber Bragg Grating

A frequency-doubling optoelectronic oscillator (FD-OEO) based on a dual-parallel Mach-Zehnder modulator (DPMZM) and a chirped fiber Bragg grating (CFBG) has been demonstrated. The DPMZM implements a carrier phase-shifted double sideband (CPS-DSB) modulation to generate a microwave signal at the second-harmonic frequency, while the CFBG ensures the oscillation of the fundamental frequency signal by tailoring the phase relationships between the optical sidebands and the carrier. As a result, self-starting 10- and 20-GHz microwave signals with low phase noises are simultaneously generated.

1.55-

Monolithically integrated long-wavelength vertical-cavity surface-emitting laser arrays of 4, 8, and 12 high-speed devices are presented. These devices have a lithographically defined pitch of 250 μm and feature a per-channel bandwidth of 10 Gb/s over 20 km of standard single-mode fiber. The output performance is very homogenous for the whole array. Emission wavelength is addressable by current-tuning without any bit-error-rate penalty. This allows highly scalable bandwidth for metro-range networks. Through the migration from coarse wavelength-division-multiplexed (WDM) to dense WDM operation, a bandwidth upgrade from 2.5 to 80 Gb/s is feasible without any further investment into the transmitter infrastructure.

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We present a reconfigurable microwave frequency measurement technique with adjustable measurement range and resolution. The key novelty of the technique is the employment of stimulated Brillouin scattering, which results in a tunable amplitude comparison function, leading to an adjustable measurement range and resolution. The proposed technique is switchable between a wideband tunable narrow measurement range (~2 GHz) with high resolution (±0.05 GHz) and a fixed wide measurement range (12 GHz) with moderate resolution (±0.25 GHz).

m VCSEL Arrays for High-Bandwidth WDM-PONs

An improved optical self-heterodyne method utilizing a distributed Bragg reflector (DBR) tunable laser and an optical fiber ring interferometer is presented in this paper. The interference efficiency can be increased by 7 dB compared with the scheme using the conventional Mach-Zehnder interferometer. The unsteady process that the beating frequency experiences in each tuning period is investigated. According to the measurement results, the wavelength and optical power of the tunable laser will be steady when the square-wave frequency is lower than 300 kHz. It has been shown that when a square-wave voltage is applied to the phase section of the tunable laser, the laser linewidths vary in a wide range, and are much larger than that under dc voltage tuning. The errors caused by the variations in the linewidth of the beat signal and optical power can be eliminated using the proposed calibration procedures, and the measurement accuracy can, therefore, be significantly improved. Experiments show that the frequency responses obtained using our method agree well with the data provided by the manufacturer, and the improved optical self-heterodyne method is as accurate as the intensity noise technique.

Brillouin-assisted microwave frequency measurement with adjustable measurement range and resolution

Software-Defined Satellite Payloads Based on Microwave Photonics! Satellite communication offers a number of distinct features that are not readily available with other means of communication, such as seamless coverage of remote and sparsely populated areas, reliable data relay for deep-space exploration, inherent multicasting and broadcasting capabilities, and reliable performance in extreme conditions (e.g., war, earthquakes, and other adverse events) [1], [2]. In recent years, the steep rise in mobile multimedia applications and increased space exploration activity have created unprecedented opportunities for innovative satellite communication. According to a report provided by the Satellite Industry Association in September 2014, the global revenue of the satellite communication industry for 2013 reached US

Improved optical heterodyne methods for measuring frequency responses of photodetectors

189.2 billion-60% of global space revenue and 4% of global telecommunications revenue [3]. Apple, Google, Amazon, Facebook, and many other large technology companies are currently seeking to bolster their satellite communication systems in the next five to ten years, fostering a continuous increase of revenue in this area.

Satellite Payloads Pay Off

This paper presents a continuously tunable microwave photonic notch filter with a complex coefficient. The complex coefficient is generated using a radio-frequency (RF) phase shifter that consists of a dual-parallel Mach-Zehnder modulator (DPMZM) and a tunable optical bandpass filter (TBPF). By simply controlling the bias voltage of the DPMZM, the frequency response of the filter can be continuously tuned over a full free spectral range (FSR) without changing the shape of the frequency response.

Continuously Tunable Microwave Photonic Notch Filter With a Complex Coefficient

We propose and demonstrate a novel reconfigurable instantaneous frequency measurement (IFM) system based on the dual-parallel Mach-Zehnder modulator (DPMZM). The IFM system can be reconfigurable with tunable measurement range and resolution by simply adjusting the dc bias voltage of the DPMZM. In principle, the measurement range could be tuned to any frequencies, which is only limited by the bandwidth of the optical transmitter and receiver employed. Alternatively, the IFM system can also work with a fixed wide measurement range and moderate resolution by generating two complementary power-fading functions.

Reconfigurable Instantaneous Frequency Measurement System Based on Dual-Parallel Mach–Zehnder Modulator

We present a novel radio-frequency (RF) photonic phase shifter based on wavelength dependence of Brillouin frequency shift. A continuous and full phase shift up to 360° at 18 GHz is achieved when the wavelength of the optical carrier is scanned from 1549 to 1554 nm using stimulated Brillouin scattering (SBS) in a 1.2-km length of dispersion-shifted fiber (DSF).

Photonic Phase Shifter Based on Wavelength Dependence of Brillouin Frequency Shift

Molecular-beam-epitaxy-grown InGaAlAs-InP vertical-cavity surface-emitting lasers with buried tunnel junction for 1.55-/spl mu/m wavelength, passivated with benzocyclobutene (BCB) and coplanar contacts are presented. The devices show 3-dB modulation frequencies above 8 GHz (small signal modulation) and wide open eye diagrams up to 10 Gb/s over more than 4.6-km ITU-T G.653 fiber (data transmission experiment).