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Fiber Brillouin amplifier intensity noise is investigated experimentally for a distributed feedback and external cavity diode laser. Since relative intensity noise is a serious performance limitation in Brillouin amplification applications, a detailed investigation is carried out with measurements of integrated overall noise and noise spectrum for different pump and signal powers. Fundamental conclusions on pump and gain depletion for different laser linewidths are drawn. High spectral resolution measurements performed within the Brillouin gain spectrum demonstrate that signal-to-noise ratio increases as the seed signal power increases. In addition, a computational model using the finite-difference time domain method is presented showing excellent agreement with the experimental results. [ABSTRACT FROM PUBLISHER]

The success in conquering the terahertz (THz) gap is subject to some facts such as maximizing the emitted power. Traditionally resonant antenna designs for continuous-wave (CW) THz photomixing include a RF choke to compensate the capacitive part of the photomixer and an antenna with a very high input impedance at its resonance to match the low value of the photomixer conductance. This communication considers that the antenna itself can provide this large impedance margin needed to directly match the photomixer, so that the RF choke can be avoided. The meander antenna constitutes an excellent candidate to achieve that goal based on the Active Integrated Antenna concept to improve both matching and radiation efficiencies. The main objective is to maximize the total efficiency and, as a consequence, the THz emitted power. A prototype working at 1.05 THz is designed and manufactured and results show a 6 dB output power improvement when compared with a conventional log-periodic antenna. [ABSTRACT FROM PUBLISHER]