Atom interferometry is an advanced optical manipulation tool of atoms in precision measurement field. Wavefront aberrations of the Raman beam have become one of the major obstacles impeding the improvement of measurement accuracy. Beforehand measurement of laser wavefront is impractical due to the further wavefront deterioration during optical mounting. In this work, we present a general method for evaluating the effective Raman wavefront that atoms experience and the corresponding phase shift of interferometric fringes. The method extracts the effective Zernike polynomial terms and reconstructs the wavefront using optimal estimation theory. The evaluation accuracy and convergence speed are discussed by simulation. The results predict the method adaptability and provide strong support on analytical and numerical reference for wavefront error compensation.
Broadband radio frequency signal generation based on ultrafast optical pulse shaping, which is a typical microwave photonic technology, has been performed. The ultrafast optical pulse starts from our home-made mode-locked laser which has a repetition rate of ~171 MHz and spans from 1524 nm to 1593 nm. Following the MLL is an optical amplifier which makes up for the loss of the photonic link. A commercial pulse shaper is introduced to flatten and shape the spectrum of the optical pulse. However, it results in a additionally frequency cutoff. Only the C-band (5 THz optical bandwidth) is used efficiently which results in waste of spectrum resources. Then, the shaped pulses travel through a 5km long optical fiber realizing frequency-to-time mapping. The RF signal is acquired from the optical intensity profile by a high-speed photodetector at last. Several different kinds of wideband RF signals are generalized from the same hardware system, such as trigonometric and linear frequency-chirped waveform from 2 GHz up to 3 GHz, These results may be of interest to the radar and communication systems with ultraband RF signals.
Multi-wavelength fiber lasers are under intense research due to their potential in many application fields
like wavelength-division-multiplexing communication, fiber-based sensing, ranging, microwave photonics
and terahertz generation, etc. In this manuscript, we will present our detailed investigation on tunable high
power multi-wavelength double-clad fiber laser pumped by high-power multimode laser diode. The fiber laser
is constructed in a ring-cavity. By adjusting the polarization-controller inside the cavity, the laser can operate
at single-wavelength, dual-wavelength and triple-wavelength regime. The maximal output power is 5.5 watt
and the conversion efficiency is 68.8%.
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