In this work, a saturable absorber (SA) was fabricated using the organic semiconductor material SFX-2,7-DDPA via spin-coating. Comprehensive microstructural analysis and optical characterization were conducted to evaluate both linear and nonlinear absorption properties. The SFX-2,7-DDPA SA exhibited outstanding saturable absorption behavior, with a measured modulation depth of 8.4%. Subsequently, the SA was successfully implemented as a modulator to realize a passively Q-switched (PQS) Tm:YAP laser. Under PQS operation, the laser achieved an average output power of 540 mW with a slope efficiency of 7.1%, emitting at a central wavelength of 1931.21 nm. The system generated stable pulses with durations below 315 ns at a repetition rate of 100.4 kHz, yielding single-pulse energies up to 5.38 mu J and peak powers reaching 17.1 W. High beam quality was confirmed by M2 values of 1.11 and 1.06 along orthogonal axes, indicating near-diffraction-limited performance. This study presents a novel application of organic semiconductors as efficient modulators in 2-mu m laser systems. (c) 2026 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Here, we introduced a passively Q-switched (PQS) Tm:YAP laser utilizing nickel-iron layered double oxide (NiFe-LDO) as a saturable absorber (SA). Following continuous tuning, a pulsed laser at 1931.22 nm was successfully produced from the continuous-wave (CW) Tm:YAP laser with NiFe-LDO-based SA. Under the CW operation, the laser exhibited an average output power of 2.1 W, which was obtained with an absorbed pump power of 8.8 W. The central output wavelength was recorded at 1967.58 nm, and this configuration resulted in a slope efficiency of 32.1 %, demonstrating effective energy conversion. When operating in the PQS mode, the laser delivered an average output power of 510 mW, achieving a slope efficiency of 9.4 %. Moreover, we noted a pulse width of only 519.1 ns at a repetition frequency of 106.9 kHz, corresponding to a single pulse energy of 3.97 mu J and a peak power of 7.65 W. The measured beam quality factors were M-x(2) = 1.14 and M-y(2) = 1.10, respectively. These findings suggest that NiFe-LDO-based SA serves as a powerful modulator, exhibiting substantial promise for ultrafast nonlinear optical applications. To the best of our knowledge, this marks the first application of NiFe-LDO as a SA in a near-infrared PQS all-solid-state laser, paving the way for future advances in this area of research.

Objective The 1.5 mu m waveband laser has attracted remarkable attention in various fields, including radar, remote sensing, laser vibration measurement, and material microprocessing, because of its low atmospheric-transmission loss and safety for human eyes. The 3 -5 mu m waveband laser has a typical "atmospheric infrared window" and fingerprint band, and it can be used for molecular-content detection, environmental detection, imaging, telemetry, and biomedicine. Owing to its high spectral purity, long coherence length, and low phase noise, a narrow-linewidth, high-beam-quality infrared laser can be better applied in gravitational-wave detection, cold atomic physics, coherent optical communication, and optical-precision detection. An optical parametric oscillator (OPO) is an effective device for frequency conversion and can directly convert the wavelength of a solid-state laser into near-and mid-infrared wavelengths. Compared to the femtosecond OPO, the picosecond OPO not only has a high average power output but also exhibits a good balance between the pulse width and narrow spectral bandwidth. Methods A schematic of the synchronous-pumping picosecond KTiOAsO4 (KTA)-OPO, used for high-power, high-beam-quality, narrow-bandwidth laser generation in the near-and mid-infrared wavelengths, is presented in Figure 1. The pump source is an all-solid-state picosecond laser based on a diode-pumped Nd:YVO4 crystal, which provides up to 18.5 W of maximum output power at 1064 nm in 15 ps pulses at a 120 MHz repetition frequency. A half-wave plate was used to rotate the polarization of the pump beam to excellently match the phase in the KTA crystal. Using a plano-concave lens with a focal length of 100 mm, the output of the pump beam was focused to similar to 63 mm at the center of the nonlinear crystal. The cavity parameters and spacing were theoretically estimated using LASCAD software. To achieve the best mode coupling of the pump and signal beams in the nonlinear crystal, the signal beam had a spot radius of 64 mu m at the center of the KTA. The 90 degrees-cut KTA crystal (5 mmx 5 mm x 30 mm) was selected as the nonlinear-gain medium, and the two end surfaces were antireflection coated for the pump (1.064 mu m), signal (1.535 mu m), and idler (3.468 mu m) beams. To achieve synchronous pumping, the OPO was configured into a signal-resonant Z-shaped standing-wave cavity using five reflective mirrors. Reflector M1 is a plane. Mirrors M2 and M3 are plane-concave mirrors with a 150 mm radius of curvature; the distance between them is 167 mm. Reflector M-4 is a concave mirror with a 500 mm radius of curvature. The output coupling mirror M5 is a concave mirror with a 1000 mm radius of curvature. M-1-M-4 are highly reflective (99.9 degrees o ) to the signal beam and highly transmissive to the pump and idler beams. The output coupling mirror (OC) M5 has a 20 degrees o transmittance and 80 degrees o reflection to the signal beam. This design not only ensures a single-resonance signal but also enables the signal and idler beam to simultaneously be stably output from the cavity. Results and Discussions By adjusting various cavity parameters, a standing-wave cavity with high stability is established, successfully achieving high-beam-quality, high-power, narrow-linewidth, and highly stable signal and idler outputs. The spatial-profile distributions of the signal and idler beams are near-Gaussian modes (Fig. 2). The beam quality factors (M-2) of the output beam are measured using the knife-edge method. The M-2 values of the signal beam in the two orthogonal directions are 1.11 and 1.12 [Fig. 3(a)], whereas those of the idler beam are 1.16 and 1.17 [Fig. 3(b)]. At the maximum pump energy of 18.5 W, 3.55 W of signal and 1.75 W of idler beams are output, with conversion efficiencies of 27.8 % and 13.6 % (Fig. 4), respectively. The extracted signal and idler beams exhibit passive power stabilities of better than 1.6 % (RMS) and 1.5 % (RMS) over 6 h (Fig. 5), respectively. The full width at half maximum (FWHM) of the signal and idler outputs are measured to be Delta lambda(s)=0.27 nm and Delta lambda(i)=0.75 nm (Fig. 6), respectively. Conclusions This study demonstrates the generation of high-beam-quality, narrow-linewidth, high-stability, and high-power ultrafast lasers in the near-and mid-infrared wavelengths by building a single-resonant signal KTA-OPO that is synchronously pumped by a 1 mu m picosecond pulsed laser. At a maximum pump energy of 18.5 W, a signal output in the near-infrared region and an idler output in the mid-infrared region are obtained, corresponding to slope efficiencies of 27.8 % and 13.6 %, respectively. By combining the excellent nonlinear characteristics of the KTA crystal and the stable resonant cavity, M2 values of 1.12 and 1.17 are achieved for the signal and idle outputs, respectively. The signal and idler beams exhibit high power stability over 6 h.

In this study, a saturable absorber (SA) was prepared by using V4C3Tx and integrated it into a resonant cavity, successfully operating it in a passively Q-switched (PQS) mode for the first time. Under PQS operation, the laser demonstrated a central wavelength of 1936 nm with a maximum average output power of 450.3 mW, a pulse width of 363.6 ns, and a pulse repetition frequency (PRF) of 98.23 kHz. A 120-min power stability at 450.3 mW test yielded a root mean square (RMS) value of 0.81%, confirming the excellent stability of the laser. In addition, the beam quality factors (M-2) were measured to be less than 1.20 at 450.3 mW. These findings indicate the promising application potential of V4C3Tx material in the 2 mu m wavelength band.

This study reports a novel MAX phase material, Mo2TiAlC2, as a passively mode-locking (PML) saturable absorber (SA) for a Tm:YAP laser operating in the 2 μm wavelength range. The systematic characterization of its nonlinear optical properties was quantitatively analyzed using I-scan methodology, demonstrating a significant modulation depth of 3.5%, which indicated strong nonlinear optical activity. Within the realm of optimal cavity conditions, a remarkable performance by the PML configuration can be discerned. A stable pulsed emission was manifested at 1937 nm, wherein an average output power reaching 620 mW was achieved. A pulse temporal span of 989.5 ps was acquired with a corresponding repetition frequency of 103.1 MHz, indicating robust mode-locked synchronization. Notably, the beam quality factors (M2) along the orthogonal spatial axes were observed with values measuring 1.12 and 1.18, respectively, indicating propagation characteristics close to those of diffraction-limited beams.

In this study, we experimentally demonstrated a passively mode-locked (PML) Tm:YAP laser utilizing a Ti3AlC2-based saturable absorber (SA). A continuous-wave mode-locked (CWML) regime was achieved when the incident pump power exceeded 13.5 W and an average output power of 1105 mW at 1937. 8 nm was realized with a slope efficiency of 5.4%. Furthermore, a pulse width of 221.6 ps was gained at a repetition frequency of 106.7 MHz, corresponding to a single pulse energy of 10.4 nJ and a peak power of 46.7 W. This is, to our best knowledge, the first application of a Ti3AlC2-based SA in achieving CWML operation for Tm:YAP lasers.

Herein, we present a picosecond-pulsed optical vortex parametric oscillator capable of generating high-power, narrow-linewidth near- and mid-infrared optical vortex outputs. The optical parametric oscillator (OPO), consisting of a KTiOAsO4 (KTA) crystal and a Z-shaped standing wave cavity formed by five mirrors, transferred the orbital angular momentum (OAM) of the pump field to the signal and idler fields. The transmission mechanism of the OAM within the signal singly resonantsingly-resonant KTA-OPO was investigated, and the OAM was controlled and selectively transferred among the pump, signal, and idler fields by adjusting the focus position of the pump beam on the KTA crystal. With an incident pump power of 17 W, the maximum average output power was 2.14 W at 1535 nm (signal vortex field) and 0.95 W at 3468 nm (idler vortex field), respectively, corresponding to optical conversion efficiencies of 20.8% and 9.2%. The spectral linewidths of the signal and idler vortex fields were 0.502 nm and 1.216 nm, respectively. To the best of our knowledge, this is the first instance of a picosecond-pulsed optical vortex parametric oscillator with a KTA crystal.

High-order Laguerre-Gaussian (LG) petal-like beams have become a topic of significant interest due to their potential application in next-generation optical trapping, quantum optics, and materials processing technologies. In this work, we demonstrate the generation of high-order LG beams with petal-like spatial profiles and tunable orbital angular momentum (OAM) in the mid-infrared wavelength region. These beams are generated using idler-resonant optical parametric oscillation (OPO) in a KTiOAsO4 (KTA) crystal. By adjusting the length of the resonant cavity, the OAM of the mid-infrared idler field can be tuned and we demonstrate tuning in the range of 0 to +/- 10. When using a maximum pump energy of 20.2 mJ, the maximum output energy of high-order modes LG(0 , +/- 5), LG(0 , +/- 8), and LG(0 , +/- 10) were 0.8, 0.53, and 0.46 mJ, respectively. The means by which high-order LG modes with petal-like spatial profiles and tunable OAM were generated from the OPO is theoretically modeled by examining the spatial overlap efficiency of the beam waists of the pump and resonant idler fields within the center of the KTA crystal. The methodology presented in this work offers a simple and flexible method to wavelength-convert laser emission and generate high-order LG modes.

Vortex beams are unique in that they have annular spatial profiles and carry orbital angular momentum. This has led to their use in applications including laser processing, microparticle manipulation and signal transmission. Off-axis vortex beams, which may be considered a subset of vortex beams, display a broader spectrum of physical characteristics in comparison with their conventional (integer-order) counterparts. In this work, we derive the equations which describe the intensity distribution of off-axis vortex beams and use these to theoretically model their spatial profile. These models are supported by experimental generation of both integer and off-axis vortex beams, and the presence of orbital angular momentum is investigated through the use of the cylindrical lens transformation method.

This work report the generation of high-order Laguerre-Gaussian (LG) modes from a nanosecond, optical vortex pumped diamond Raman laser. This system is capable of generating first-Stokes (lambda 1st = 1240 nm) LG modes with topological charge (& ell;) of up to 26 and second-Stokes (lambda 2nd = 1485 nm) LG modes with topological charge of up to 22, when pumped using a first-order vortex beam. The maximum first- and second-Stokes LG mode energies are measured to be 0.5 and 1 mJ, respectively, when pumping with energy of 19.8 mJ. High-order LG modes can be formed through the coherent superposition of orthogonal LG beams with opposite azimuthal indices. This work demonstrates the generation of high-order LG modes from an optical vortex pumped Diamond Raman laser. This system is capable of generating first-Stokes (lambda 1st = 1240 nm) and second-Stokes (lambda 2nd = 1485 nm) LG modes with topological charge (& ell;) of up to 26 and 22. image

Owing to their remarkable characteristics, two-dimensional (2D) layered, MAX phase materials have garnered significant attention in the field of optoelectronics in recent years. Herein, a novel MAX phase ceramic material (Mo2TiAlC2) was prepared into a saturable absorber (SA) by the spin-coating method for passively Q-switching (PQS), and its nonlinear optical absorption properties were characterized with a Tm:YAlO3 (Tm:YAP) nanosecond laser. The structure characteristics and composition analysis revealed that the Mo2TiAlC2 material exhibits a well-defined and stable structure, with a uniform thin film successfully obtained through spin coating. In this study of a PQS laser by employing a Mo2TiAlC2-based SA, an average output power of 292 mW was achieved when the absorbed pump power was approximately 4.59 W, corresponding to a central output wavelength of 1931.2 nm. Meanwhile, a stable pulse with a duration down to 242.9 ns was observed at a repetition frequency of 47.07 kHz, which is the narrowest pulse width recorded among PQS solid-state lasers using MAX phase materials as SAs. Our findings indicate that the Mo2TiAlC2 MAX phase ceramic material is an excellent modulator and has promising potential for ultrafast nonlinear photonic applications.

In this paper, we present a picosecond pulsed, synchronously pumped optical parametric oscillator producing vortex beam output with tunable wavelengths in the near- to mid-infrared range. The system utilizes a Nd:YVO4 picosecond pulsed solid-state laser emitting at a wavelength of 1.064 µm to pump a Z-shaped, singly resonant OPO which contains a MgO:PPLN crystal with a fan-shaped grating. The wavelength tuning characteristics of the OPO output are examined both as a function of the MgO:PPLN grating period and crystal temperature. The orbital angular momentum of the pump field can be selectively transferred to either the signal or idler fields by appropriately adjusting the location of the MgO:PPLN crystal within the OPO cavity. The maximum output power of the signal and idler vortex fields are 5.12 W and 3.46 W, respectively, for an incident pump power of 19 W.

We propose a modified difference weak measurement scheme that permits precise measurements of the magneto-optical Faraday effect. By making normalized difference processing for a set of post-selected light intensity, a linear-response regime with a significant weak-value amplification effect is established. In the proof-of-principle experiment, we measure the magnetic intensity using the polarization system and achieve precision at the order of similar to 10(-7) T. Our scheme can be applied to measure other magneto-optical effects, providing a method for future ultra-sensitive sensing and metrology in magnetic physics.

We present a high-power, widely tunable, synchronously pumped picosecond pulsed optical parametric oscillator (OPO) generating emissions in the near to mid-infrared wavelength ranges. The OPO is pumped using a Nd:YVO4 picosecond pulsed laser and utilizes a fan-shaped, multi-grating MgO doped PPLN crystal (MgO:PPLN). The system generates near to mid-infrared output across the wavelength range 1.3–5 µm, with a high overall conversion efficiency of 75.15%.

The Nb2AlC material has attracted more and more attention in optoelectronics due to its excellent optical properties. Herein, the Nb2AlC-based saturated absorber (SA) was fabricated by ultrasonic thermal dissolution method and spin coating means, and a passively mode-locked (PML) Tm:YLF laser was perfectly demonstrated with the SA. With an incident pump power of 21.63 W, a 0.379-W average output power and a 200-ps pulse width were achieved at 1872.1 nm, corresponding to a per pulse energy of 3.15 nJ and a peak power of 15.75 W. In addition, the beam quality factors were measured to be 1.04 and 1.05 in the horizontal direction and vertical direction.

A passively Q-switched (PQS) Tm: YAP laser in the 2 p.m waveband is introduced. A linear cavity structure of the Tm: YAP laser is chosen in the experiment. A laser diode with an output central wavelength of 792 nm is used as the pump source, and a saturable absorber prepared by a new two-dimensional material of black phosphorus is used as a PQS modulation device for the Tm: YAP laser. In the continuous wave mode, an output power of 1.0 W is obtained with an output central wavelength of 1994. 8 nm from the Tm: YAP laser under the pump power of 8. 8 W, corresponding to a slope efficiency of 17. 3%. Under the PQS regime, an average output power of 0. 9 W and a minimum pulse width of 1. 3 mu s at 135. 8 kHz are acquired from the Tm: YAP laser at 1986. 7 nm under the pump power of 8. 8 W, corresponding to a slope efficiency of 14. 2%. In addition, the beam quality factor of M-x(2) =1. 10 and M-y(2) =1. 06 are measured from the PQS Tm: YAP laser under an average output power of 0. 9 W.

Metal-organic frameworks (MOFs) have received significant attention owing to their nanometer-sized void spaces, large surface areas, and tunable bandgaps. The properties of MOFs can be adjusted by doping other metal motifs or organic ligands. MOFs are widely employed in nanodevices and optical thin film materials; however, their third-order nonlinear optical (NLO) properties are rarely investigated, and their application in solid-state laser (SSL) has not been reported. In this paper, the NLO properties of Ni-doped MOFs are investigated comprehensively, wherein the value of the nonlinear refractive index and that of the real part of the third-order nonlinear optical susceptibility are obtained, i.e., 6.10 × 10 −9 cm 2 /W and 6.20 × 10 −7 esu, respectively. Consequently, an SSL that coupls Ni-doped MOFs with a saturable absorber (SA) is constructed. An average output power of 0.68/1.10 W is acquired with a 1.5% or 2.5% transmission of the output coupler (OC) under a passive Q-switch mode operation, corresponding to a per pulse energy of 6.29/10.90 μJ. When coupled with Tm: YAP, the as-constructed SSL exhibits a stable and short pulse (1.97 μs) at 1987.5 nm, indicating that Ni-doped MOFs can be applied to broadband SAs to achieve a fast photonic in the near-infrared spectra.

Ultrafast pulsed lasers (UPL) have critical applications in many fields, where a saturable absorber (SA) is an essential part. Perovskites have attracted much attention in SAs due to their unique structural features, which have not been mentioned in ultrafast pulsed lasers yet. In this paper, Pb(Zr-x,Ti1-x)O-3 (PZT) perovskite material is used as the SA equipment in an M-type passively mode-locked solid Tm:YAP UPL. Benefiting from the unique structure, the UPL possesses a similar to 2 mu m laser output and a repetition frequency of 102.04 MHz, as equipped in a 1466 mm length cavity. In addition, the output power of the laser is 0.721 and 0.297 Win continuous wave and passive mode-locked operation, respectively. Meanwhile, the laser gets the narrowest pulse width of 820.73 ps along with a peak power of 3.55 W, and it expresses quality factors of M-x(2) = 1.09 and M-y(2) = 1.12. at the highest average output power. These advantages indicating that the PZT can be an ideal SA material in a solid UPL.

A continuous-wave (CW) and passively Q-switched (PQS) Yb,Ho:LuVO4 laser pumped by a 978.6-nm laser diode (LD) is demonstrated. The maximum output power of 131 mW at 2059.78 nm in CW regime is achieved with a pump power of 3.01 W, corresponding to a slope efficiency of 10.74%. Under PQS mode operation, an average output power of 45 mW and a shortest pulse width of 100 ns were acquired by a semiconductor saturable absorber mirrors, and for all we know, this is the first report about the PQS Yb,Ho:LuVO4 laser. In addition, a maximum energy per pulse of 12.6 nJ with a pulse repetition frequency of 7.692 MHz was obtained, corresponding to a peak power of 58.5 mW. The beam quality factor was measured to be M-x(2) = 1.10 and M-y(2) = 1.10 from the PQS Yb,Ho:LuVO4 laser.

Herein, we present a compact Tm:YAG laser which was Q-switched by a V2CTx saturable absorber. When the laser was running in the passively Q-switched operation, it could stably output pulse trains with central wavelengths of 2012.51 and 2015.11 nm. The output power, pulse width and repetition rate generated from the Q-switched laser was 130 mW, 3.85 mu s, and 10.83 kHz, respectively. Meanwhile, a peak power of up to 3.12 W and a pulse energy of 12 mu J were also obtained. In addition, the dual-wavelength operation of the MXene Q-switched laser has been observed for the first time.