Self-referenced octave-wide subharmonic GaP optical parametric oscillator centered at 3 µm and pumped by an Er-fiber laser: erratum.

This erratum reports a correction to the labeling of Figs. 2(b) and 3(b) in the original manuscript, Opt. Lett.42, 4756 (2017)OPLEDP0146-959210.1364/OL.42.004756.

Self-referenced octave-wide subharmonic GaP optical parametric oscillator centered at 3 µm and pumped by an Er-fiber laser.

We report an octave-wide mid-IR spectrum (2.3-4.8 µm) obtained from a subharmonic optical parametric oscillator (OPO) based on a newly developed nonlinear crystal, orientation-patterned gallium phosphide (OP-GaP), which was synchronously pumped by a femtosecond 1560 nm fiber laser. We proved that the octave-wide output is in the form of a single frequency comb. The observed f-to-2f frequency beats, originating directly from the OPO, can be used for self-referencing and phase locking of the pump laser comb with no need for supercontinuum generation. With an average output power of ∼30 mW, this setup might be beneficial for a variety of spectroscopic applications in the mid-IR.

Mid-wave infrared beam steering based on high-efficiency liquid crystal diffractive waveplates.

We demonstrated two liquid crystal diffractive waveplates: one optimized for near-infrared (1.06 µm), and another for mid-wave infrared (MWIR, 3~5 µm). By employing a low loss liquid crystal mixture UCF-M3, whose absorption loss is below 2% in the 4~5 µm spectral region, the grating achieves over 98% diffraction efficiency in a broad MWIR range. To switch the grating, both active and passive driving methods can be considered. In our experiment, we used a polymer-stabilized twisted nematic cell as the polarization rotator for passive driving. The obtained rise time is 0.2 ms and decay time is 10 ms.

Harmonic mode locking with reduced carrier-envelope phase noise in ytterbium-doped fiber laser.

We experimentally explored the influence of passive harmonic mode locking on the temporal and spectral features of a ytterbium-doped fiber laser. Similar dependences of free-running linewidth of the laser carrier-envelope offset frequency (f0) on the intracavity net dispersion were observed for the fundamental-, second-, and third-order mode-locking states. Due to the reduction of nonlinear effects and supermode phase locking that balanced the third-order dispersion in the fiber cavity, the third-order harmonic mode-locking exhibited the narrowest free-running f0 linewidth of ~120 kHz in the near-zero net dispersion regime.

High-power Yb-fiber comb with feed-forward control of nonlinear-polarization-rotation mode-locking and large-mode-area fiber amplification.

We report on a simple scheme to precisely control carrier-envelope phase of a nonlinear-polarization-rotation mode-locked self-started Yb-fiber laser system with an average output power of ∼7 W and a pulse width of 130 fs. The offset frequency was locked to the repetition rate of ∼64.5 MHz with a relative linewidth of ∼1.4 MHz by using a self-referenced feed-forward scheme based on an acousto-optic frequency shifter. The phase noise and timing jitter were calculated to be 370 mrad and 120 as, respectively.