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 Physics , 2000, Abstract: We have characterized a semiconductor amplifier laser system which provides up to 200mW output after a single-mode optical fiber at 780nm wavelength. The system is based on a tapered semiconductor gain element, which amplifies the output of a narrow-linewidth diode laser. Gain and saturation are discussed as a function of operating temperature and injection current. The spectral properties of the amplifier are investigated with a grating spectrometer. Amplified spontaneous emission (ASE) causes a spectral background with a width of 4nm FWHM. The ASE background was suppressed to below our detection limit by a proper choice of operating current and temperature, and by sending the light through a single-mode optical fiber. The final ASE spectral density was less than 0.1nW/MHz, i.e. less than 0.2 % of the optical power. Related to an optical transition linewidth of $\Gamma/2\pi=6$ MHz for rubidium, this gives a background suppression of better than -82dB. An indication of the beam quality is provided by the fiber coupling efficiency up to 59 %. The application of the amplifier system as a laser source for atom optical experiments is discussed.
 Physics , 2006, DOI: 10.1364/OL.31.001337 Abstract: A tapered semiconductor amplifier is injection seeded by a femtosecond optical frequency comb at 780 nm from a mode-locked Ti:sapphire laser. Energy gains over 17 dB (12 dB) are obtained for 1 mW (20 mW) of average input power when the input pulses are stretched into the picosecond range. A spectral window of supercontinuum light generated in a photonic fiber has also been amplified. Interferometric measurements show sub-hertz linewidths for a heterodyne beat between the input and amplified comb components, yielding no detectable phase-noise degradation under amplification. These amplifiers can be used to boost the infrared power in f-to-2f interferometers used to determine the carrier-to-envelope offset frequency, with clear advantages for stabilization of octave-spanning femtosecond lasers and other supercontinuum light sources with very limited power in the infrared.
 Applied Sciences , 2013, DOI: 10.3390/app3010288 Abstract: The study of wavelength tunability for the gain media Yb:CaF 2 and Yb:YAG in a regenerative amplifier configuration, was performed by using a simulation code previously benchmarked with real data. The results demonstrate that both materials have potential for amplifying pulses up to the milijoule level for wavelengths around 1048–1049 nm. In light of this, we propose and evaluate their performance as gain media in the pre-amplifier of a hybrid chain operating at 1053 nm.
 Physics , 2014, Abstract: A wavelength spacing tunable, multiwavelength Q-switched mode-locked (QML) fiber laser in an erbium-doped fiber cavity based on graphene oxide deposited on tapered fiber is proposed by choosing the diameter and length of the taper, graphene oxide thickness and cavity dispersion, in which the wavelength spacing could be tuned by pump power. The evolutions of temporal and spectral with different pump strengths are investigated. Results show that the tunability of the multiwavelength laser can be interpreted by the bound states of QML laser resulting from a mutual interaction of dispersion, nonlinear effect, insertion loss, and pump power. To the best of our knowledge, it is the first experimental observation of bound states of QML, which provides a new mechanism to fabricate tunable multiwavelength laser.
 Physics , 2010, DOI: 10.1364/OE.18.009258 Abstract: We report on the phase-locking of two diode lasers based on self-seeded tapered amplifiers. In these lasers, a reduction of linewidth is achieved using narrow-band high-transmission interference filters for frequency selection. The lasers combine a compact design with a Lorentzian linewidth below 200 kHz at an output power of 300 mW. We characterize the phase noise of the phase-locked laser system and study its potential for coherent beam-splitting in atom interferometers.
 Physics , 2013, DOI: 10.1063/1.4811196 Abstract: Laser cooling of atoms usually necessitates several laser frequencies. Alkaline atoms, for example, are cooled by two lasers with a frequency difference in the Gigahertz range. This gap cannot be closed with simple shifting techniques. Here, we present a method of generating sidebands at 6.6 GHz by modulating the current of a tapered amplifier which is seeded by an unmodulated master laser. The sidebands enable trapping of 1.1*10^9 Rubidium 87 atoms in a chip-based magneto-optical trap. Compared to the direct modulation of the master laser, this method allows for an easy implementation, a fast adjustment over a wide frequency range and the simultaneous extraction of unmodulated light for manipulation and detection. The low power consumption, small size and applicability for multiple frequencies benefits a wide range of applications, reaching from atom-based mobile sensors to the laser cooling of molecules.
 Physics , 2014, DOI: 10.1038/ncomms6025 Abstract: We demonstrate the Ramsey analogous experiment known as coherent control, taking place along an electrically-driven semiconductor optical amplifier operating at room temperature.
 Chen-Ling Ying;Ching-Hung Chang;Ya-Ling Houng;Hai-Han Lu;Wen-Shing Tsai;Heng-Sheng Su PIER C , 2009, DOI: 10.2528/PIERC09101503 Abstract: A down-link CATV/fiber-to-the-home (FTTH) and up-link FTTH transport system employing a reflective semiconductor optical amplifier (RSOA) as wavelength reuse and remodulation schemes is proposed and experimentally demonstrated. By using -1 side mode injection-locked/optoelectronic feedback techniques, brilliant performances of carrier-to-noise ratio (CNR), composite second-order (CSO), composite triple beat (CTB), and bit error rate (BER) were obtained for down-link transmission; low BER value was also achieved for up-link transmission over a 50-km single-mode fiber (SMF) transmission. Such a CATV/FTTH transport system is suitable for broadband access fiber networks.
 Physics , 2013, DOI: 10.1364/OL.38.001161 Abstract: We have experimentally studied the multiple side-band generation for two-frequency components injected into a tapered amplifier and demonstrated its effects on atomic laser cooling. A heterodyne frequency-beat measurement and a Fabry Perot interferometer have been applied to analyze the side-band generation with different experimental parameters, such as frequency difference, injection laser power and tapered amplifier current. In laser cooling potassium40 and potassium41 with hyperfine splitting of 1.3GHz and 254MHz, respectively, the side-band generation with a small frequency difference has a significant effect on the number of trapped atoms.
 Mathematics , 2014, Abstract: We study the effect of noise on the dynamics of passively mode-locked semiconductor lasers both experimentally and theoretically. A method combining analytical and numerical approaches for estimation of pulse timing jitter is proposed. We investigate how the presence of dynamical features such as wavelength bistability affects timing jitter.
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