Are ternary halides useful materials for nonlinear optical applications?

Tl3PbBr5: A possible crystal candidate for middle infrared nonlinear optics

“…Despite that Tl 3 PbBr 5 crystallizes in a non centrosymmetric space group, the w ð2Þ ijk tensor elements of which are not all reduced to zero by Kleinman symmetry conditions, it was notoriously ignored in Ref. [11], where the potential application of several complex halides to nonlinear optics is questioned. According to us, what makes this compound a priori worth studying is that not only does it have low phonon energy and chemical inertness to water vapour, but also interesting non centrosymmetric properties in both the high-and roomtemperature phases.…”

Periodically poled materials for long wavelength infrared (LWIR) NLO applications

“…We have identified that several binary halides, that are promising candidate for frequency conversion applications and cover a wide range of transparency. Hagemann and Weber [13] published an important analysis on the structure of these materials. They discussed the physical, chemical and crystallographic aspect and developed a concept for preparing nonlinear optical halides.…”

Growth, crystal structure, thermal properties and optical anisotropy of Tl4CdI6 single crystals

“…High optical transmittance of the ternary halides, which can sometimes reach as far as up to 30-50 μm, makes them promising materials for the long-wavelength IR range and, in particular, for the far-IR nonlinear optics (see [9][10][11]). However, as shown by many earlier studies (see, e.g., [12][13][14]), the compounds of the A 4 BX 6 family crystallise in a centrosymmetric point symmetry group 4/mmm, which hinders nonlinear optical applications and requires additional measures such as, e.g, periodic poling [10,11].…”

“…However, as shown by many earlier studies (see, e.g., [12][13][14]), the compounds of the A 4 BX 6 family crystallise in a centrosymmetric point symmetry group 4/mmm, which hinders nonlinear optical applications and requires additional measures such as, e.g, periodic poling [10,11]. In this respect it is also important that there has been a controversy concerning the availability of inversion centre in the most thoroughly investigated compound Tl 4 HgI 6 , and the authors of the works [15,16] have stated that it is described by the acentric group 4mm.…”