Compact Mode-locked Fiber Laser Research Articles

Porous nickel oxide micron polyhedral particles for high-performance ultrafast photonics

As a member of organic porous crystal structure, metal organic frameworks (MOFs) material has more unique properties due to its large specific surface area, high porosity, diversified structure and functions, it has been successfully applied in new energy, microelectronics, chemical reaction medical science and other fields. However, no study about NiO-MOF for the ultrafast optics application has been reported till now. In this paper, NiO-MOF polyhedral particles is prepared by hydrothermal method and successfully applied to ultrafast photonics. The modulation depth of NiO-MOF is 18.98 % through a dual-balance detection system. Most importantly, the 109th harmonic solitons are realized for the first time based on NiO-MOF in a compact mode-locked fiber laser at 1.55 μm, the fiber laser has pulse duration of 766 fs and repetition frequency of 413 MHz. As far as we know, this is the first time NiO-MOF has been applied to realize harmonic mode-locking at the fs level of more than 400 MHz. Due to the rich variability of MOFs structure, this study successfully provides support for the application of MOFs material in advanced photonics.

All-Fiber Mode-Locked Laser Utilizing 45°-Tilted Fiber Grating-Based Polarization Beam Splitter

We have experimentally demonstrated an all-fiber mode-locked laser by using a 45°-tilted fiber grating (45°-TFG) based in-fiber polarization beam splitter (PBS). Based on the nonlinear polarization rotation (NPR), the slanted refractive index modulation structure of the 45° TFG is able to tap the pluses out from the side face of the fiber. The central wavelength of the laser is 1559.9 nm and the period of pulse train is 156 ns, corresponding to the fundamental repetition rate of 6.79 MHz, the pulse energy of 0.26 nJ and the pulse duration of 1.06ps. Additionally, the laser shows a high degree of polarization (DOP) output of 99.8%. This mode-locked fiber laser with single polarization mode output is reliable during long-term operation and thus promising for many practical applications. As a proof of principle, the demonstrated laser can provide neat solution in designing compact mode-locked fiber laser.

PbS Nanoparticles for Ultrashort Pulse Generation in Optical Communication Region

AbstractLead sulfide (PbS) has attracted great attention due to its unique electronic, optical, and chemical properties. In particular, the narrow bandgap of PbS (≈0.37 eV) makes it very suitable for the ultrafast application in optical communication or even longer wavelength region. In this work, PbS nanoparticles' (NPs) dispersion without any polymer is utilized as saturable absorber (SA) to generate ultrafast pulse in a fiber ring laser for the first time. The characterization and nonlinear properties of PbS NPs are investigated experimentally. PbS NPs are deposited on a flange to compose a nonlinear device. The nonlinear absorption is measured by a power‐dependent method with a modulation depth of 12.2%. Most importantly, PbS NPs can be applied for the ultrafast photonics applications. A compact mode‐locked fiber laser with 1.01 ps pulse duration, 2.93 nm spectral width, and 3.97 MHz repetition rate at 1533 nm is successfully achieved with long time stability. The output laser is detected with a good stability for more than 1 month without any degradation. This work can demonstrate that the PbS NPs' dispersion is indeed a new and excellent photonics material for SA photonics, photoconductive detection, and optical modulator, etc.

High-performance multi-megahertz optical coherence tomography based on amplified optical time-stretch.

As the key prerequisite of high-speed volumetric structural and functional tissue imaging in real-time, scaling the A-scan rate beyond MHz has been one of the major pursuits in the development of optical coherence tomography (OCT). Along with a handful of techniques enabling multi-MHz, amplified optical time-stretch OCT (AOT-OCT) has recently been demonstrated as a viable alternative for ultrafast swept-source OCT well above MHz without the need for the mechanical wavelength-tuning mechanism. In this paper, we report a new generation of AOT-OCT demonstrating superior performance to its older generation and all other time-stretch-based OCT modalities in terms of shot-to-shot stability, sensitivity (~90dB), roll-off performance (>4 mm/dB) and A-scan rate (11.5 MHz). Such performance is mainly attributed to the combined contribution from the stable operation of the broadband and compact mode-locked fiber laser as well as the optical amplification in-line with the time-stretch process. The system allows us, for the first time, to deliver volumetric time-stretch-based OCT of biological tissues with the single-shot A-scan rate beyond 10 MHz. Comparing with the existing high-speed OCT systems, the inertia-free AOT-OCT shows promises to realize high-performance 3D OCT imaging at video rate.

Dissipative soliton generation from a graphene oxide mode-locked Er-doped fiber laser

We demonstrated dissipative soliton obtained from a graphene oxide mode-locked Er-doped fiber laser, which operated in normal dispersion cavity by employing the dispersion compensation fiber. The highly chirped pulses at the repetition rate of 19.5 MHz can be compressed from 11 ps to 542 fs by using single mode fiber. Numerical simulations were in good agreement with the experimental results. The hydrophilic graphene oxide with easier fabrication shows great potential to be a novel low-cost saturable absorber in reliable and compact mode-locked fiber laser system.

High-throughput characterization of linear and nonlinear optical properties in composition-spread (Sr,Ca) 2CuO 3 thin-films

We have constructed a high-throughput spectrometer and a nonlinear optical tester used for the characterization of combinatorial thin-film libraries. The optical spectrometer consists of a multi-channel detector and an automated bidimensional translation stage. The transmission spectrum of an area of 0.5 mm×2 mm can be measured for a wavelength range of 280–900 nm. Our nonlinear optical tester uses a compact mode-locked fiber-laser as an excitation source. The laser beam is focused by a graded index lens, the fundamental light is filtered out, and the third-harmonic (TH) light is detected by a photomultiplier. The data collection and the motion of the stepping motor-driven stage are synchronized. Typical measurement time for a composition-spread thin-film is 5 min. A demonstration is shown for a composition-spread thin-film of one-dimensional cuprate (Sr x Ca 1− x ) 2CuO 3 with gigantic third-order optical nonlinearity.