Zuxing Zhang

Multiwavelength fiber laser with fine adjustment, based on nonlinear polarization rotation and birefringence fiber filter

We have proposed and demonstrated a multiwavelength fiber laser based on nonlinear polarization rotation (NPR). The mechanism for stable room-temperature multiwavelength operation contributes to the ability of the intensity-dependent loss in NPR to effectively alleviate mode competition. In addition, through tuning the birefringence fiber filter, the lasing wavelength can be accurately tuned in the free spectrum range of the in-line periodic filter.

Tunable self-seeded multiwavelength Brillouin-Erbium fiber laser with enhanced power efficiency

We have demonstrated a tunable multiwavelength Brillouin- Erbium fiber laser (BEFL), which is internally self-excited without additional Brillouin pump. With the use of a birefringence loop mirror filter, the laser output wavelength can be tuned through modifying the filtering profile of the birefringence filter. As a result, the generation of more than 70-wavelength combs with uniform power distribution has been obtained in ~11-nm tuning range. And the wavelength of combs can be tuned in the bandwidth of the Sagnac loop filter. Also, utilizing the spare port of the 3-dB coupler as the output port, the laser output power efficiency has been enhanced by 13 dB.

Tunable multiwavelength SOA fiber laser with ultra-narrow wavelength spacing based on nonlinear polarization rotation

A tunable multiwavelength fiber laser with ultra-narrow wavelength spacing and large wavelength number using a semiconductor optical amplifier (SOA) has been demonstrated. Intensity-dependent transmission induced by nonlinear polarization rotation in the SOA accounts for stable multiwavelength operation with wavelength spacing less than the homogenous broadening linewidth of the SOA. Stable multiwavelength lasing with wavelength spacing as small as 0.08 nm and wavelength number up to 126 is achieved at room temperature. Moreover, wavelength tuning of 20.2 nm is implemented via polarization tuning.

Passive harmonically mode-locked fiber ring laser with long single-mode fiber and its application for high-resolution measurement of fiber length

Passive harmonically mode-locked fiber ring laser with long single-mode fiber SMF has been demonstrated. With the increase of nonlinearity due to the incorporation of a long SMF, it is found that the laser can operate in harmonic mode-locking states with various repeti- tion rates. Furthermore, based on the passively mode-locked fiber ring laser, a novel and simple technique for fiber length measurement with resolution on the order of centimeters has been proposed. The fiber length can be easily obtained from the fundamental cavity frequency of the mode-locked fiber laser because the transit time in a laser cavity is exactly proportional to the cavity length.

Multiwavelength Brillouin /Erbium fiber laser with adjustable wavelength spacing

A multiwavelength fiber laser with adjustable wavelength spacing has been demonstrated. The hybrid gain combining nonlinear gain of self-excited stimulated Brillouin scattering and linear gain of EDF can sustain multiwavelength output. With a birefringence fiber loop filter, the wavelength spacing can be adjusted by changing the length of birefringence fiber.

Unstable nonlinear spectral filtering balance in ANDi passive modelocking fiber lasers

Wave breaking of similariton in all-normal-dispersion (ANDi) fiber lasers is studied theoretically and experimentally. The nonlinear intra-cavity spectral filtering balance becomes unstable with greatly-decreased ASE noise tolerance under excessive nonlinearity, and then wave breaking occurs.

Polarization-dependent output states of a fiber laser with nonlinear polarization rotation

A fiber laser with two different polarization-dependent output states is demonstrated. On the one hand, intensity-dependent loss in a nonlinear optical loop mirror, induced by nonlinear polarization rotation, can balance mode competition of a homogeneous broadening gain medium, and thus allows for stable room-temperature multiwavelength generation. On the other hand, intensity-dependent transmission can act as an equivalent saturable absorber, which results in passive mode locking of the fiber laser. It may thus serve two functions: passive mode locking and multiwavelength emission.

Observation of two-color pulses in a passively mode-locked erbium-doped fiber ring laser

The operation of a passively mode-locked erbium-doped fiber ring laser in two-color pulse mode has been experimentally observed. The experiments demonstrate that the wavelengths of two-color pulses can be switched among three wavelength bands. Through carefully controlling the polarization states of the laser cavity, various modulation patterns of the two-color pulses are obtained, which are due to the interaction of two different-wavelength pulses. Single- and three-color pulses are also observed. Multiwavelength oscillation is ascribed to the wavelength-dependent transmission induced by birefringence, and can synchronously mode-lock through nonlinear polarization rotation.

Multiwavelength emission and passive mode-locking from a same fiber laser with nonlinear optical loop mirror

Fiber laser with two polarization-dependent output states is demonstrated. On one hand, nonlinear polarization rotation induced intensity-dependent loss of nonlinear optical loop mirror can balance mode competition of homogenous broadening gain medium, and thus allows for stable room-temperature multiwavelength generation. On the other hand, intensity-dependent transmission can act as an equivalent saturable absorber, which results in passively mode-locking of fiber laser. It may be a potential multifunction fiber laser.