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Ultra-fine Frequency Tunable Brillouin Fiber Laser And Its Application In Microwave Photonics

Posted on:2012-03-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z J WuFull Text:PDF
GTID:1118330362458377Subject:Optics
Abstract/Summary:PDF Full Text Request
Single-frequency Brillouin fiber lasers (SBFL) have been attracting extensive interests because of their compactness, robustness, stableness and their characteristics of linewidth narrowing and noise suppression. They have important potential applications in many fields, such as fiber sensing systems, high-resolution spectroscopy and microwave photonics, and so on. Though great improvement of their single-frequency ability has been achieved nowadays, their tuning ability still should be further studied for exploring more applications.Our research focuses on the construction of single-frequency Brillouin fiber lasers with precise tuning accuracy and systematically studying their applications in the field of microwave/millimeter-wave signal generation. Several original results are obtained and the main results in this thesis are listed as follows:1. Using the tunable semiconductor laser source (TLS) as the Brillouin pump, we studied and demonstrated the SBFL with linewidth of less than 5 kHz. At the same time, the linewidth of the Brillouin pump was also carefully measured and the linewidth narrowing and noise suppression effect in the SBFL had been theoretically and experimentally studied.2. Ultra-fine optical-frequency tunable SBFL based on acoustic domain processing was achieved. The output frequency of the SBFL equals to the Brillouin pump frequency minus the fiber Brillouin frequency shift (BFS). Applying tunable strain to the fiber as the Brillouin gain medium in the SBFL, its BFS would be changed and the SBFL output frequency can be tuned. The experimental results show the tuning accuracy of the SBFL can be achieved to 60 kHz which is three orders better than the finest conventional tunable lasers based on optical filters.3. Continuous tuning in one free spectral range (FSR) of the SBFL was achieved and studied. The experimental results show in a FSR of 19.82 MHz, the continuous tuning range of the SBFL is 6.22 MHz, and the mode hopping is 13.6 MHz.4. We propose and demonstrate a simple scheme to generate highly stable microwave signal by utilizing a dual-wavelength Brillouin fiber laser (DBFL). Without using any frequency-stabilized mechanism on the light source, the generated microwave signals exhibit high stability both for the injected pump wavelength variation and the environmental temperature fluctuation. The linewidth of the microwave signal is less than 10 kHz. And the measured results show that the frequency fluctuation of the microwave signal is less than 0.1 MHz.5. Optical generation of microwave signal with precise tuning ability by heterodyning the outputs of cascaded single-frequency Brillouin fiber lasers (BFLs) was achieved and studied. The microwave signals are with high frequency of tens of GHz and exhibit high stability. The microwave frequency tuning accuracy is about 100 kHz. And the linewidth of the microwave signal is 2.8 kHz.
Keywords/Search Tags:Single-frequency fiber laser, stimulated Brillouin scattering, ultrafine optical-frequency tunability, optical generation of microwave/millimeter wave signal
PDF Full Text Request
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