Table 1 Physical data of HMQ-TMS crystals in comparison with benchmark HMQ-T, OH1, DAST and ZnTe crystals. For THz experiments, 0.16-mm-thick HMQ-TMS, 0.58-mm-thick HMQ-T, 0.27-mm-thick OH1, 0.5-mm-thick DAST and 1.0-mm-thick ZnTe crystals were used

wavelength of maximal absorption in methanol, λ_max (nm)

439

439

424

475

-

microscopic first-order hyperpolarizability, β_max (10⁻³⁰ esu)

185

169

93

194

-

macroscopic optical nonlinearity, |β_iii^eff| (10⁻³⁰ esu)

185

155

63

161

electro-optic coefficient

-

-

r₃₃ = 75 pm/V at 785 nm

r₁₁ = 77 pm/V at 800 nm

r₄₁ = 4 pm/V at 680 nm

solubility 40°C (g/100 g methanol)

2.24

0.78

3.74

3.73

-

bulk crystal growth of large size

easy

very difficult

easy

easy

-

thickness control

easy

very difficult

very difficult

very difficult

-

formation of hydrated phase

no

no

no

hydrate

-

cut-off wavelength

< 595 nm

< 595 nm

< 640 nm

< 680 nm

peak-to-peak THz E-field (kV/cm)

57^[a]

31^[a]

-

21^[a]

peak-to-peak E-field (× 1.0 mm thick ZnTe)

2.7^[a]

2.6^[b]

1.5^[a]

0.56^[c]

1.0^[a]

upper cut-off frequency (amplitude > 1.0) (THz)

6.0^[a]

3.4^[b]

5.3^[a]

-

3.8^[a]

absorption at near 1.1 THz

weak

strong

weak

strong

weak