Rytterholm8815

A new, to the best of our knowledge, 3D additive manufacturing technique utilizing particle-loaded ink jet printing to fabricate transparent ceramic YbYAG planar waveguides for laser gain media was demonstrated. Rheological optimization of YAG particle-loaded inks resulted in successful droplet formation and printing resolution. Planar waveguides composed of a YbYAG guide encased in undoped YAG cladding were printed with guide thicknesses ranging between 25 and 350 µm and consolidated to high optical quality via solid-state sintering. Sufficiently low optical (1-3%/cm) and intermodal scatter allowed single-mode propagation with a core/clad index difference of $\Delta n\sim5.0 \times 10^- 4$ (corresponding to 3 at.% Yb). The waveguides were cladding-pumped longitudinally with a 940 nm diode array resulting in 23.6% slope efficiency in 2 ms pulsed operation.A tunable fiber polarizer based on the selectively silver-coated large-core suspended-core fiber (LSCF) was proposed. A thin silver layer was coated on the inner surface of two opposite air holes of the LSCF by the chemical liquid-phase deposition method. The $y$-polarized light (parallel to the two silver-coated air holes) will excite surface plasmon resonance and experience large transmission loss, while the $x$-polarized light does not, resulting in a fiber polarizer. By varying the liquid filled in the microchannels of the LSCF, the operating wavelength can be tuned in the visible and near infrared region along with the surface plasmon resonance wavelength. The dependence of the polarization characteristics on the fiber length was experimentally investigated. The maximum polarization extinction ratio (PER) of 20.1 dB, 19.6 dB, and 18.3 dB and insertion loss (IL) of 2.24 dB, 2.56 dB, and 2.08 dB are achieved with the optimal fiber length of 16 cm at the operating wavelengths of 565.4 nm, 626.7 nm, and 739.7 nm, respectively. Compared with the multimode fiber-based polarizers reported previously, the proposed selectively silver-coated LSCF polarizer exhibits higher PER and lower IL.High-power solid-state lasers with good beam quality are attracting great attention on account of their important applications in industry and military. However, the thermal effects generated in the laser host materials seriously limit power scaling and degrade the beam quality. Thermal lensing and thermally induced wavefront deformation are the main causes of the beam quality deterioration. Here we investigate the performance of a zero thermal expansion (ZTE) solid-state laser gain material. In a proof-of-principle experiment, an $a$-cut rod $\rm Nd\!\!\rm YAlO_3$ (NdYAP) perovskite crystal is chosen to be the gain medium for ZTE around 180 K. The laser performance spanning the temperature range from 80 to 290 K is studied. The maximum output power and minimum threshold pump power were obtained at a temperature of 180 K. Moreover, the measured thermal focal power and peak-to-valley value of the wavefront distortion also reach a minimum at this temperature, an additional benefit from the crystal's ZTE coefficient. We envisage that these results will open a new route towards the development of high-power and high-beam-quality lasers through the use of ZTE gain materials.We report on the first, to the best of our knowledge, LED-pumped femtosecond regenerative amplifier. It is based on a CrLiSAF crystal pumped by 2240 blue LEDs via a CeYAG luminescent concentrator. The amplifier was seeded by pulses from a Tisapphire oscillator at 835 nm temporally stretched from 90 fs to 100 ps. At the output of the regenerative amplifier, we obtain 1 mJ pulse energy at a 10 Hz repetition rate, given by the frequency of the LED-pumping module. After compression, we obtain 100 fs pulses with a spectral bandwidth of 10 nm at 835 nm.A room-temperature watt-level continuous-wave-output power mid-infrared fiber laser operating at $\lambda\sim 3\; \unicodex00B5\rm m$ is demonstrated using a $\rm Ho^3 +/\rm Pr^3 +$ co-doped $\rm AlF _3$ based glass fiber as a gain fiber. This fixed-wavelength laser had maximum output power of 1.13 W with a slope efficiency of 10.3% and a long-term operating stability of $\gt40\;\min $ without any additional packaging or active thermal management. A fiber laser with tunability from 2.842 to 2.938 µm showed a maximum output power of 110 mW.We report a supercontinuum generation (SCG) in a waveguide that spontaneously forms without an etching process during the deposition of a core material on a preformed $\rmSi\rmO_2$ substructure. The mechanism of dispersion control for this new, to the best of our knowledge, type of waveguide is analyzed by numerical simulation, which results in a design rule to achieve a target dispersion profile by adjusting the substructure geometry. SCG is experimentally demonstrated with a waveguide made of $\rmA\rms_2\rmS_3$, chalcogenide glass, which has low material absorption over the mid-IR range. A dispersion-controlled waveguide with a length of 10 mm pumped with 77 pJ pulses at a telecommunication wavelength of 1560 nm resulted in a supercontinuum that extends by more than 1.5 octaves.Diffraction gratings that redirect light propagating in a channel waveguide to an on-chip slab are emerging as important building blocks in integrated photonics. Such distributed Bragg deflectors enable precise shaping of slab confined beams for a variety of applications, including wavelength multiplexing, optical phased array feeding, and coupling interfaces for on-chip point-to-point communications. However, these deflectors suffer from significant losses caused by off-chip radiation. In this Letter, we show, for the first time, to the best of our knowledge, that off-chip radiation can be dramatically reduced by using the single-beam phase matching condition and subwavelength metamaterial refractive index engineering. We present a deflector design with losses below 0.3 dB, opening a path toward new applications of distributed Bragg deflectors in integrated photonics.In this erratum, we correct Fig. Bafilomycin A1 in vitro 4 of our Letter [Opt. Lett.46, 1740 (2021)OPLEDP0146-959210.1364/OL.422095]. This does not change the scientific conclusions of the original Letter.