The influence of the fourth-order dispersion coefficient on the behavior of parametric gain and saturation power of a one-pump fiber optical parametric amplifier over a signal wavelength span in the presence of fiber random dispersion fluctuations was investigated. The output signal power for the parametric gain calculation was obtained by numerically solving the three-coupled amplitude equations. Based on the calculations of the parametric gain over a variation of the signal wavelength, it is found that the saturation power behavior is dependent on the behavior of parametric gain. The manipulations of signal wavelength and the fourth-order dispersion coefficient changed the phase-matching condition, thereby affecting the resulting parametric gain and saturation power.

To overcome the beam squint in wide instantaneous frequency, we review a number of system-level optical controlled phase array antennas for beam forming. The optical delay network based on a fiber device in terms of topological structure of an N-bit optical switch, fiber grating, high-dispersion fiber, and vector-sum technology is discussed, respectively. Lastly, an integrated circuit is simply summarized.

In this paper, we propose an additional noise-free, independent center frequency and bandwidth tunable optical filter based on stimulated Brillouin scattering (SBS) losses. By suppressing the out-of-band signal with two broadened symmetric SBS losses, tunable pass bandwidths from 500 MHz to 9.5 GHz and the independent center frequency tunability are demonstrated. Considering the limited SBS interaction in the center frequency range, a flat-top response with minimum 0.3 dB ripple is achieved. Assisted by the extra suppression from polarization pulling, a maximum selectivity of 20 dB and an ultrahigh 250 dB/GHz roll-off are reached. A gain-based SBS filter adds noise to the filtered signal. However, for our proposed filter setup, no additional noise is detected due to the transparency in the passband. Considering the wide independent bandwidth and center frequency tunability, flat-top response, and low-noise characteristic, our proposed filter can be perfectly used as a supplement of most commercialized conventional tunable optical single bandpass filters, whose minimum bandwidth is limited by 10 GHz.

In this Letter, an effective method using a mode selective coupler (MSC), which is composed of a three-core fiber is presented to generate optical vortices (OVs). The conversions of OVs with different topological charges, 0→±1 and 0→±3, are simulated in detail. We also prove that a higher-order topological charge can be obtained simply by changing the parameters of the fiber to increase the number of modes in the fiber. The polarization of OVs can be controlled as well.

All-fiber signal combiner is a key component for augmenting the fiber laser power. Presently the reported 7×1 signal combiners are all have output fibers with core diameters larger than 100 μm. In order to improve the beam quality of the combiner, a fiber with smaller core of 50 μm diameter is chose to be the output fiber. An all-fiber 7×1 signal combiner is fabricated with measured power transmission efficiency around 99% for each port. The beam quality is improved and the measured M2 are around 6 which are matched well with the theoretically calculated results.

The factors that influence the generation of a high-quality optical frequency comb (OFC) based on a recirculating frequency shifter (RFS) due to the maximum output power and noise figure of Er-doped fiber amplifier (EDFA) are studied theoretically and experimentally. Based on the theoretical analysis, numerical simulations and experiments under different EDFA parameters have been carried out. The results show that the performance of the OFC based on a RFS can be improved effectively by optimizing the maximum output power and the noise figure of the EDFA.