Ultrafast fiber laser based on HfSe₂ saturable absorber

Abstract

We demonstrate the HfSe2 saturable absorber (SA) for the generation of ultrafast pulse laser. The HfSe2 SA device is fabricated by integrating HfSe2 nanosheets (NSs) with a microfiber. The material and optical characteristics of HfSe2 NSs show their high quality. The nonlinear optical absorption of HfSe2 SA is measured with a modulation depth of 5.8%. Stable soliton mode-locked laser based on HfSe2 SA is realized at the central wavelength of 1561.43 nm with pulse duration of 297 fs and the maximum pulse energy of 2.68 nJ. Our soliton fiber laser has a maximum output power of 48.5 mW with a high slope efficiency of 12.8%, which indicate that HfSe2 is a good candidate of SA for high efficient ultrashort pulses generation.

Low‐Power Memristive Logic Device Enabled by Controllable Oxidation of 2D HfSe2 for In‐Memory Computing

“…The A 1g peaks of pristine HfSe 2 before the oxidation (red line in Figure 1e) at 199 cm −1 are in good agreement with previously reported results. [ 30,32 ] After 5 min oxygen plasma treatment, the intensity of HfSe 2 A 1g peak position is significantly reduced, and a new HfO x Raman peak (≈255 cm −1 ) appears [ 33 ] (blue line in Figure 1e). Raman spectra of HfSe 2 oxidation by air exposure and O 2 ‐plasma treatment with different thicknesses confirm that the oxidation by O 2 ‐plasma treatment is more thorough than by spontaneous air exposure, as shown in Figure S3 (Supporting Information).…”

High-sensitive phototransistor based on vertical HfSe2/MoS2 heterostructure with broad-spectral response

“…Figure 3(c) shows the transfer characteristics of the device under dark and different wavelengths illumination with 0.78 mW/cm 2 at V ds = 0.5 V. The significant enhancement of the photocurrent can be observed for the NUV and visible light illumination. It has been reported that both multilayer MoS 2 and multilayer HfSe 2 have relatively strong light absorption from NUV to visible region, [3,[32][33][34] which induces an increase of photogenerated carriers in the HfSe 2 /MoS 2 heterojunction, resulting in a significant enhancement of the photocurrent. Under the illumination of NIR, there is a slight increase in the photocurrent, which is related to the weak absorption tail of the indirect band gap semiconductors MoS 2 and HfSe 2 .…”

2D Semi‐Metallic Hafnium Ditelluride: A Novel Nonlinear Optical Material for Ultrafast and Ultranarrow Photonics Applications

“…The obtained mode-locking threshold was ≈170% lower compared to the other Hf-based SAs. [14,15] Due to the excellent nonlinear optical properties of HfTe 2, it was possible to get the modelocking operation in such a low threshold pump power. The low-threshold mode-locking allowed for a laser to be operated at lower overall power, reducing the potential for heat damage to the laser's components and permitting the design of self-starting mode-locking operations essential for high-speed communication, spectroscopy, and material processing.…”

“…Among the other semi-metallic TMDs material, hafnium ditelluride (HfTe 2 ) is getting attention due to its significant application in medical sterilization, gas sensor, and superconductor. [10][11][12] 2D-HfTe 2 , a semi-metallic compound belonging to the VIB group of TMDs, [13] has garnered little attention in the field of nonlinear optics and photonics despite the fact that other materials in this group, such as HfS 2 [14] and HfSe 2 , [15] have been extensively studied for their effectiveness as saturable absorbers (SAs) in the generation of ultrafast lasers. The majority of work on HfTe 2 to date has largely focused on its basic characteristics, such as its structure and stoichiometry, [16] theoretical and experimental electronic band structure, [17] electric transport properties, [18] and doping-affected band structure.…”