We report on the nonlinear coupling between the mechanical modes of a nanotube resonator.The coupling is revealed in a pump-probe experiment where a mode driven by a pump force is shown to modify the motion of a second mode measured with a probe force. In a second series of experiments, we actuate the resonator with only one oscillating force. Mechanical resonances feature exotic lineshapes with reproducible dips, peaks, and jumps when the measured mode is commensurate with another mode with a frequency ratio of either 2 or 3. Conventional lineshapes are recovered by detuning the frequency ratio using the voltage on a nearby gate electrode. The exotic lineshapes are attributed to strong coupling between the mechanical modes. The possibility to control the strength of the coupling with the gate voltage holds promise for various experiments, such as quantum manipulation, mechanical signal processing, and the study of the quantum-toclassical transition.
Abstract:In this paper, we present the generation of high peak-power picosecond optical pulses in the 1.26 μm spectral band from a repetitionrate-tunable quantum-dot external-cavity passively mode-locked laser (QD-ECMLL), amplified by a tapered quantum-dot semiconductor optical amplifier (QD-SOA). The laser emission wavelength was controlled through a chirped volume Bragg grating which was used as an external cavity output coupler. An average power of 208.2 mW, pulse energy of 321 pJ, and peak power of 30.3 W were achieved. Preliminary nonlinear imaging investigations indicate that this system is promising as a high peak-power pulsed light source for nonlinear bio-imaging applications across the 1.0 μm -1.3 μm spectral range.
Abstract:We report picosecond pulse generation with high peak power in the range of 3.6 W from monolithic passively mode-locked tapered quantum-dot laser diodes, exhibiting low divergence and good beam quality.These results were achieved using a gain-guided tapered laser geometry. The generation of picosecond pulses with high average power up to 209 mW directly from such tapered lasers is also demonstrated, corresponding to 14.2 pJ pulse energy (14.65 GHz repetition rate). A comparison between the mode-locking performance of these tapered lasers incorporating either 5 or 10 layers of InAs/GaAs self-organized quantumdots in their active layer is also presented.
We report on the development of a new generation of high power ultrashort pulse quantum dot lasers with tapered gain section. Two device designs are proposed and fabricated, with different total lengths and absorber to gain section length ratios. These designs have been informed by numerical simulations of the dynamic mode locking regimes and their dependence on the structural parameters. One device design demonstrated a record high peak power of 17.7 W with 1.26 ps pulse width and a second design enabled the generation of a Fourier limited 672 fs pulse width with a peak power of 3.8 W. A maximum output average power of 288 mW with 28.7 pJ pulse energy was also attained. In addition, the integrated timing jitter of 2.6 ps and far field patterns are demonstrated.
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