Investigation of tellurium for frequency doubling with CO<inf>2</inf>lasers

Midwavelength Infrared Photoluminescence and Lasing of Tellurium Elemental Solid and Microcrystals

“…Instead of being used as an emitter, the Te crystal has been used as a nonlinear optical medium for second harmonic generation, such as frequency doubling of a 10.6 μm CO 2 laser to 5.3 μm. 29 Considering the many efforts toward finding a midwavelength IR (MWIR) luminophore as a reference in the MWIR region, similar to the role of rhodamine in the visible region, it is imperative to measure the MWIR bandgap PL of the Te elemental crystal. In addition, such information can be used for gaining further understanding of optical properties of species such as artificially synthesized Te crystals: nanoparticles, 23,30−33 nanorods, 21,34,35 nanowires, 24,26,32,34−37 nanotubes, 22,25,35−38 nanobelts, 22,39 two-dimensional tellurene, 40−42 three-dimensional structures, 11,43,44 and chiral nanostructures.…”

“…The Te crystal is known to be a nonlinear optical medium for second harmonic generation, such as frequency doubling of a CO 2 laser at a wavelength of 10.6 μm to 5.3 μm. 29 This nonlinear SHG is generated through phase matching in the Te crystal with the spiral nonsymmorphic (D 3 ) point group symmetry. Interestingly, we observed unprecedented second harmonic (2ω) and the third-harmonic (3ω) lasing at 5519 cm −1 (1.81 μm) and 8277 cm −1 (1.21 μm), respectively, in addition to the fundamental at 2760 cm −1 (ω = 3.62 μm) from the rodshaped microcrystals in the absence of the bulk Te at the bottom in Figure 4E.…”

“…Unfortunately, further study of the lasing, such as threshold temperature, threshold photoexcitation fluence, or new emissive properties arising from different morphologies of the material, has not been reported. Instead of being used as an emitter, the Te crystal has been used as a nonlinear optical medium for second harmonic generation, such as frequency doubling of a 10.6 μm CO 2 laser to 5.3 μm . Considering the many efforts toward finding a midwavelength IR (MWIR) luminophore as a reference in the MWIR region, similar to the role of rhodamine in the visible region, it is imperative to measure the MWIR bandgap PL of the Te elemental crystal.…”

“…Second Harmonic Generation and Third Harmonic Generation of Lasing of Tellurium Microcrystals . The Te crystal is known to be a nonlinear optical medium for second harmonic generation, such as frequency doubling of a CO 2 laser at a wavelength of 10.6 μm to 5.3 μm . This nonlinear SHG is generated through phase matching in the Te crystal with the spiral nonsymmorphic ( D 3 ) point group symmetry.…”

Unveiling Ultrafast Carrier Dynamics of Tellurium Microcrystals by Two-Color Asynchronous Sampling Infrared Transient Absorption Spectroscopy

“…Since such MIR-transition materials are interesting for optoelectronic applications, exciton recombination processes in the intraband and interband transitions of colloidal quantum dots and chalcogenide semiconductors with a narrow bandgap have been studied extensively. Among various MIR-active materials, tellurium (Te) has attracted particular attention because its bandgap energy was found to be around 0.32 eV, and it shows interesting properties, such as optical nonlinearity, − thermoelectricity, − photoconductivity, and piezo-electricity. , In addition, it has been demonstrated that Te microcrystals and nanowires can exhibit a strong MIR emission and even a lasing property. , However, a detailed study of the carrier dynamics in photoexcited Te microcrystals has yet to be reported.…”