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Photonic Generation High Statility Millimeter Wave And Remote Distribution Technology

Posted on:2016-10-06Degree:DoctorType:Dissertation
Country:ChinaCandidate:D N SunFull Text:PDF
GTID:1108330503493772Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
Since the beginning of this century, microwaves(millimeter wave) interference antenna array technology has brought a revolution for microwave system. Compared to single microwave antenna system, it maks a breakthrough in receiving sensitivity and identify ability. Interferometric antenna array synchronizes antennas to combine coherently the signal received from different base antennas. In this way, it achieves a several fold increase in antenna receiving sensitivity and resolution, realizing observation effect as increasing aperture of a single antenna. According to the principle of interference, the theory detection capability of interferometric antenna array almost equal to the longest baseline for single antenna aperture. In addition, interferometric antenna array can be adjusted through the microwave beam phase. In this way, it effectively overcomes the problem of large aperture antenna pointing adjustment. Interferometric antenna array has become an important means of modern deep space exploration and protection of radar net by its good performance, robustness, save the cost of construction work, flexibility, and plays a more and more important role in today’s national defense construction, deep space science.Synchronization is the foundation of antenna array antenna interference, the key point is distribution high stability and low phase noise local oscillator singal from center, so that each antenna could combine coherently. However, with the array antenna working frequency and coverage increase, the frequency distribution may need up to hundreds of GHz, the distribution of distances increase tens to hundreds of kilometers. The traditional coaxial transmission line is limited by transmission loss and difficult to support such a long distance transmission. To generate a high stable and low noise of millimeter wave local oscillator signal and distribution over long distance is facing a great challenge. In recent years, microwave photonic technology provides an effective way to solve these problems. For example, optical beating technology can be used to generate millimeter, submillimeter and terahertz(THz); Optical fiber can be used to realize long-distance transmission because of its low loss(0.2 d B/km) and wide bandwidth characteristics.Based on the technology of microwave photons(millimeter wave) generation and distribution, the main problems are deterioration of signal stability and phase noise induced by optical fiber transmission phase disturbance. For example, effected by external environment(such as temperature, strain, vibration etc.) changes, a 6 km communication optical fiber buried underground, the change of transmission delay could up to 2 ns when the temperature varys 20 Co. For a 10 GHz signal, phase shift corresponding to 200p. This paper aimed at phase stable generation and transmission of millimeter wave over optical fiber, put forward innovations in the following aspects:1. Phase detection of millimeter wave based on Dual-Heterodyne MixingMillimeter wave signal phase detection is a prerequisite for the realization of the phase control. Electronic millimeter wave phase detection device is limited by frequency, accuracy, phase noise. Therefore, by study of phase mapping between optical carrier and microwave, we put forward a phase error detection method based on double heterodyne mixing. In this method, millimeter wave is carried by a pair of phase locked optical carriers, mm wave signal corresponding to the phase difference of the two optical carrier. First of all, the phase of optical carried millimeter wave signal and reference are converted to two intermediate frequency by optical heterodyne mixing, and then through the electric heterodyne mixing, obtained two intermediate frequency signal phase difference. The phase information reflects millimeter wave signal phase variations. Compared with the traditional scheme, this method makes breakthrough in three aspects: firstly, do not need high speed photoelectric detection, bandwidth is not limited, low phase noise and high efficiency; secondly, high efficient mixing, high sensitivity; thirdly, double heterodyne mixing, insensitive to the laser phase noise and high precision.2. Optical carried millimeter wave signal phase control based on frequeny modulationMillimeter wave phase control is used to correction phase variation induced by fiber disturbance, is another key technology of phase stabilized fiber distribution. The traditional electronic phase controller is limited by phase control range, precision, speed and frequency. Therefore, we propose a millimeter wave phase control method based on optical frequency modulation. The basic principle is tuning one optical carrier by using acousto-optic frequency shifter(AOFS). The realization of frequency tuning of millimeter wave signal, so as to realize unlimited phase control range. Compared with the traditional scheme, this scheme achieves breakthrough in three aspects: first, unlimited phase control range; second, do not need high frequency device, frequency is unlimited; third, high tuning rate.3. High stability optical carried millimeter wave signal generationGeneration of millimeter wave signals is the prerequisite for long distance distribution, including the use of optical frequency comb, extracting two phase locked optical carriers from the optical frequency comb. Then realizing generation of the ultra high frequency(up to a few THz) by a heterodyne beat frequency millimeter wave generation. However, the main difficult problem is: in the optical carrier extraction process, two optical carrier is inevitable to experience different light paths, resulting in the millimeter wave signal phase vibration. So, it is difficult to obtain high stability millimeter wave signal. The core problem is lack of millimeter wave phase detection and effective phase control, especially for frequencies up to hundreds of GHz. The photonic phase detection and control of millimeter wave is proposed in this paper, combining the closed-loop feedback control technology. It effectively solves the phase instability problem and generates the 1THz signal, the single sideband phase noise is less than-57 d B/Hz @1 Hz,-47 d B/Hz@ 0.1 Hz frequency offset, the phase error in the 0.01Hz~1MHz frequency range is less than 5 mrad.4. Long-distance distribution of optical carried millimeter wave over fiberAfter generation millimeter wave signal, this paper has realized 100 GHz/60 km indoor optical fiber phase stable transmission, the transmission frequency stability is better than 1.6?10-16@1000s; Realization of 300GHz/25 km of dual indoor optical fiber phase stable transmission, transmission frequency stability is better than 1.6?10-16@1000 s averaging time; realizing a 1 THz/42 km telecom cable phase stable transmission, transmission frequency stability better than 1?10-15@1000 s averaging time. Compared with the reported technique, this thesis is not only makes important progress in frequency, distance, but also realized hundreds Hz tracking bandwidth and unlimited phase control range because of using of rapid and unlimited phase control range. Therefore, the system can correct severe phase perturbation of optical fiber link and has the good environmental carrying capacity without deep buried transmission fiber underground, and greatly promoting the practicability of the technology.
Keywords/Search Tags:Interferometric antenna array, microwave photonics, phase detection, phase control, photonic millimeter wave signal generation, distribution of millimeter wave signal over optical fiber
PDF Full Text Request
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