College of Precision Instrument and Opto-electronics Engineering, Institute of Laser and Opto-electronics, Tianjin University, Tianjin, China.
Opt Lett. 2013 Jul 15;38(14):2581-3. doi: 10.1364/OL.38.002581.
Tuning of the dielectric permittivity spectra of iron-doped strontium titanate (SrTiO3:Fe) single crystals in an external optical field is investigated at room temperature by means of terahertz time-domain spectroscopy. Application of the optical field leads to an appreciable tuning of the permittivity, which reaches up to 3.8%. The observed behavior is interpreted in terms of soft-mode hardening due to the anharmonic character of its potential. We also find that the change of refractive index has a linear relationship on scale with the applied light power. These findings are attributed to the internal space charge field of photorefraction caused by the excited free carriers.
室温下通过太赫兹时域光谱研究了外光场中铁掺杂钛酸锶（SrTiO3:Fe）单晶介电常数谱的调谐。光场的应用导致介电常数可显著调谐，最大可达 3.8%。观察到的行为可以用由于其势的非谐性导致软模变硬来解释。我们还发现，折射率的变化与所施加的光功率呈线性关系。这些发现归因于受激自由载流子引起的光折变的内空间电荷场。
