Acceptable composition-ratio variations of a mixed crystal for nonlinear laser device applications

Abstract

A theory is developed to predict some crucial parameters that optimize the performance of mixed nonlinear crystals in nonlinear devices. These include acceptable variations of the composition ratio of the parent crystals and the optimal as well as acceptable interaction lengths for any interaction. The theory is successfully applied to make necessary predictions for the newly developed LiIn(Se(x)S(1-x))2 crystal for second-harmonic and optical parametric generation.

Optical, thermal, electrical, damage, and phase-matching properties of lithium selenoindate

“…Another similar fit for the 0.5…10 µm spectral range appeared in [51,66] but its origin is unknown. An alternative measurement of the refractive indices of red color LISe from 0.633 to 10 µm was published in [19], together with two-pole Sellmeier equations, which were also reproduced elsewhere [52], and another index measurement with deep red LISe was used to create a further Sellmeier set specified for the 0.5-12 µm spectral range and based again on two poles [20,21], see also [67,68], but it is unclear if a refinement with SHG experimental angles in the 9.2-9.6 µm spectral range (X-Z plane) was used for its derivation.…”

“…Explicit expressions for noncollinear phase-matching in the principal planes of a biaxial crystal can be found in [81] and calculations of non-collinear group velocity matching for arbitrary wave vector directions in [82,83]. Some phase-matching properties of the mixed compounds LiIn(S 1-x Se x ) 2 were calculated in [20,21,67,68].…”

Improved growth and characterization of AgGa1−xInxSe2 crystals

“…However, it is a well-known fact that in mixed crystals grown by standard crystal growth techniques, there are always variations in the composition ratio of the two ternary end members of the solid solution system along the direction of growth. For example, in AgGa 1Àx In x Se 2 crystals a minimal variation of 1.5% has been found along the 40.7-mm long central parts of ingots with 80 mm in length [3]. What is more, AgGa 1Àx In x Se 2 has an anomalous thermal expansion behavior, expanding along the c-axis as it cools from melting point to room temperature.…”

A novel solid solution LiGa(S1–x Se x )2 for generating coherent ultrafast mid-IR sources

“…Although it is advantageous to choose the composition ratio to optimize the optical FC process of the mixed crystals, an appreciable phase mismatch is possibly induced by compositional variation inside them. We have proposed the concept of having an acceptable composition ratio to estimate the influence of the compositional variations on the PM in the FC process [15,16]. The ACR will then be considered for the LGSSe in the following part.…”

“…Due to the recent reinvestigation of the refractive indices of LGS and LGSe by Kato et al [8,9], it is necessary to thoroughly evaluate the mixture based on its excellent ultrafast frequency conversion (FC) performance. For a solid solution, the compositional discrepancy should be suppressed enough to realize the expected demonstrations in FC applications [15,16]. We then need to analyze how the compositional ratio in LGSSe influences the phase matching (PM) and the GVMM properties of ultrashort pulses.…”