Structure-terahertz property relationship and femtosecond laser irradiation effects in chalcogenide glasses

We report structure-terahertz (THz) property relationship for various non-oxide chalcogenide glasses including unary (vitreous selenium (Se)), binary (arsenic sulfide (As-S), arsenic selenide (As-Se), and germanium selenide (Ge-Se)), and ternary (germanium arsenic selenide (Ge-As-Se)), systems along with commercially available AMTIR-1, IRG 22, and IRG 24 Ge-As-Se glasses. This comprehensive study is the first of its kind to combine Raman spectroscopy to examine structural units, connectivity, and glass network and terahertz time-domain spectroscopy (THz-TDS) to record the THz refractive index, n(THz), across a broad THz bandwidth. THz-TDS was carried out at Alfred University (AU) and National Institute of Standards and Technology (NIST), ulti-mately providing confidence in n(THz) values measured at AU. Vitreous Se, = 2.0, record the minimum THz refractive index value of all Se-containing glasses. As-S and As-Se binary glasses have the highest measurable THz refractive index value at = 2.4. Ge-Se binary glasses measure increased THz refractive index as in-creases, with the maximum at = 2.8. Ternary Ge-As-Se glasses record the maximum THz refractive index value at = 2.5 for Ge10As30Se60. Low-repetition rate femtosecond laser irradiation (approximate to 1 KHz, approximate to 40 fs, and approximate to 70 mW) was used to modify As-S and As-Se glass systems, where Raman and THz-TDS were used to observe minimal structural and THz refractive index values changes, respectively. Long-wave infrared (LWIR) (e.g., 10 mu m)-THz (e.g., 1.0 THz) refractive index correlation is presented for all binary and ternary studied chalcogenide glasses. Such a correlation is valuable for predicting and designing chalcogenide glasses for integrated optical applications across THz and IR regions.

Automated summary

In this study, the structure-terahertz (THz) property relationship of various non-oxide chalcogenide glasses, including unary, binary, and ternary systems, was investigated. Raman spectroscopy was used to examine the glass structure, while terahertz time-domain spectroscopy (THz-TDS) was used to measure the THz refractive index. The study found that vitreous selenium had the lowest THz refractive index value, followed by arsenic sulfide and arsenic selenide glasses. Germanium selenide glasses showed an increased THz refractive index with increasing germanium content. A correlation between long-wave infrared and THz refractive index was also presented for all studied chalcogenide glasses, which is useful for designing integrated optical applications.