Chieh Hu

Subfemtosecond hybrid synchronization between ultrafast Yb and Er fiber laser systems by controlling the relative injection timing

We report experimental as well as theoretical investigation of the key factors that influence the relative timing jitter between hybrid synchronized ultrafast Yb and Er fiber laser systems. Experimental results show that, within the achievable synchronization range, the synchronization performance varies significantly with the relative injection timing between the 1 μm master and 1.5 μm slave pulses. This observation is in agreement with the insights obtained from the theoretical analysis, which identifies the retiming effect as a function of the initial condition of the master-slave pulse collision. By controlling the relative injection timing with a low-bandwidth intracavity feedback, relative timing jitter as low as 0.87 fs (within 1.9 MHz bandwidth) is successfully obtained.

Passive synchronization between self-similar Yb-Fiber and stretched-pulse Er-fiber mode-locked lasers

Passive synchronization is demonstrated between the self-similar Yb-fiber and the stretched-pulse Er-fiber mode-locked lasers. The pulse repetition rates of the two mode-locked lasers can keep locked when multiple-pulse bound states or periodic pulse collisions occur.

Self mode-locking sub-nano second pulse laser in all-fiber configuration

A self mode-locking (SML) ring cavity laser system with the Yb-doped fiber (YDF) was demonstrated. When the gain fiber was disturbed, the phenomenon of SML was observed. The system can produce the laser pulse width which is smaller than 1 ns without any modulation process such as polarization controller and dispersion compensation.

The study of embedded reflection gratings for distributively-pumped ytterbium-doped fiber lasers

Embedded reflection gratings for distributed pumping by laser diode bar in Yb-doped fiber lasers are studied. The best optimal coupling efficiencies of >92% and >82% are obtained in binary and blazed gratings, respectively. At 915-nm pumping, fabrication and alignment tolerances are analyzed.

Analysis of a spatially dispersive displacement sensor utilizing an AlGaInP chip

We present a demonstration and analysis of an industrialized design of a spatially dispersive displacement sensor, which is composed of an AlGaInP gain chip in visible range, optical assembly, and a spectrum analyzer. The sensor utilizes the spatial dispersion of focus from the optical assembly and wavelength spectrums deviation induced by the displacement of the target. As a result, the sensor delivers a quick and simple way of measuring displacement. By adapting the magnification and resolution of the optical assembly, a displacement sensor with a middle measurement range, ~10 microm, was obtained. However, we should note that 25 nm resolution is limited by the bandwidth and temperature fluctuation of the gain chip.