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By using optical single sideband modulation, we demonstrated instantaneous frequency measurement, which would be useful to monitor wideband radio signals with agile frequency change.
Directly modulated laser can be used as phase modulator due to chirp effect. However, accompanying amplitude modulation also results. By using EA Modulator in combination, light amplitude may be compensated enabling both amplitude and phase modulation of lightwave, which is an alternative method to conventional IQ modulator. Since light phase is proportional to intensity, we propose cumulative phasebalance...
We present a method to achieve vector modulation in an electroabsorption modulator with help of a directly modulated laser. We discuss the challenges involved and demonstrate the combined phase and amplitude modulation theoretically and experimentally using a commercial electroabsorption modulator integrated laser.
We investigate the feasibility of an electroabsorption modulator integrated laser as a digital coherent transmitter. The laser and EAM sections are used as phase and amplitude modulators respectively. We discuss the challenges involved and demonstrate the combined phase and amplitude modulation on a commercial device.
Optical-to-electric (OE) conversion devices such as photo-detectors, photo-receivers, etc. play important roles in optical fiber systems. Recently, multi-level modulation formats are commonly used for high-speed transmission systems. Thus, preciseness of OE conversion is very important as well as conversion efficiency and response time of such devices. The important figures, which specify the performance...
We demonstrate that our recently proposed chirp measurement technique can be applied to the measurement and visualization of the small-signal dynamic chirp characteristics of modulators in vector space for the first time. Both discrete modulators and those integrated in externally modulated laser modules can be characterized by this method. The results agree with existing method to the first order...
We present a high-spectral efficiency fronthaul system for the transmission of millimeter-wave and multiple-input multiple-output (MIMO) signals in future mobile networks. The transmission of an interband carrier aggregation and a 2 × 2 MIMO LTE-A signal over the system is successfully demonstrated.
This paper describes a concept of wired and wireless seamless links which can transfer waveforms over various transmission media including optical fibers, millimeter-waves, etc. The seamless links would enhance resilience and reduce latency.
In order to measure frequency responses of O/ E conversion devices such as photodiodes (PDs), we developed a measurement instrument named lightwave frequency response analyzer (LFRA). LFRA, which is based on a heterodyne technique utilizing an optical modulator, provides precise measurement solution with cost effective instrument. Measured results of two individual LFRAs show standard deviations less...
This paper demonstrates frequency response characterization of a directly modulated laser diode (bandwidth 2.5GHz) using a calibrated photodetector (bandwidth 15 GHz). This work complements our previous work in obtaining frequency response of both E/O and O/E components where only simple equipment setup is required. We discuss the issues affecting the accuracy. The results are compared with those...
We propose a novel method to measure chirp of an electro-absorption modulator in vector space due to intensity modulation at any frequency using optical homodyne quadrature demodulation technique. Chirp parameters are directly obtained in the small-signal vector space, enabling practical chirp assessment for advanced modulation optical transmission.
We propose a novel method to measure chirp of an electro-absorption modulator at any frequency using optical homodyne quadrature demodulation technique. Chirp parameters are directly obtained in the small-signal vector space, enabling practical chirp assessment for advanced modulation optical transmission.
We propose and experimentally demonstrate a seamlessly converged radio-over-fiber (RoF) and millimeter-wave system at 90 GHz for high-speed wireless signal transmission. We successfully transmit and demodulate standard orthogonal frequency-division multiplexing-based wireless local access network (WLAN) signals, long term evolution eNB conformance test models, and long term evolution advanced signals...
A two-wavelength emission laser has been fabricated using semiconductor quantum dots as the gain medium. A beat signal of ∼100 GHz was observed using Michelson interferometer configuration, indicating that these emissions occurred simultaneously.
We analyze the errors of a newly proposed measurement method on optoelectronic frequency response of photodiodes, which uses a high-extinction ratio Mach-Zehnder modulator to generate a two-tone stimulus lightwave. Five major error factors are identified and analyzed quantitatively. The result shows that the evaluated combined uncertainty is expected to be less than 0.5 dB.
We demonstrate frequency response measurement technique of photodiodes using standard Mach-Zehnder Modulator (MZM). The technique is based on heterodyne detection principle where two-tone light, whose frequency separation is in Microwave frequency range, is used to stimulate the photodiode. The MZM, with typical on-off extinction ratio of 30 dB in optical domain, is used to generate two-tone light,...
This presentation focuses on high-speed frequency control of radio-wave and lightwave signals using optical modulation. Frequency multiplication in optical modulators also plays important roles. Optical two-tone signals whose frequency separation can be up to 160 GHz would be useful for reference signals in array antennas, photodetector estimation, etc. In addition, this technique can be applicable...
10-Gb/s/ch frequency-division-multiplexing (FDM) radio-over-fiber (RoF) signal generation and free-space transmission in W-band (75–110 GHz) are successfully demonstrated. The FDM quadrature-phaseshift-keying (QPSK) signals with 3 channels are optically generated and transmitted over 30-cm radio link. Digital signal processing with W-band mixer realizes successful demodulation of its FDM radio signal.
We demonstrated W-band RoF signal generation with high-extinction-ratio optical modulation. Frequency quadruple technique with optical band elimination filter realizes frequency-stabilized W-band two-tone optical signal generation and its separation by AWG.
40-Gb/s W-band 16-QAM radio-over-fiber signal is optically synthesized using dual-polarization QPSK modulator. Its wireless transmission within FEC limit is demonstrated with optical self-heterodyne detection and digital signal processing.
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