Adiabatic frequency conversion driven by the electro-optic response of potassium tantalate niobate mixed crystals

钽铌酸钾混晶电光响应驱动的绝热变频

• 批准号: 451963068
• 负责人: Privatdozent Dr. Ingo Breunig
• 金额: --
• 依托单位: Institut für Mikrosystemtechnik (IMTEK)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/451963068?language=en
• 关键词: Adiabatic; frequency; conversion; driven; electro

In this project, we plan to realize and investigate an optical frequency converter that shifts the frequency of laser light by several 10 THz (> 50 nm at 1 micrometer wavelength). Here, 100 % of the pump photons shall be converted on the nanosecond time scale and in a single system for all wavelengths from the visible to the edge of the mid infrared. The magnitude of the frequency shift follows an applied electric voltage such that almost arbitrary temporally varying shifts can be realized by voltage modulation, e.g. linear frequency chirps.This shall be enabled by adiabatic frequency conversion. Its acoustic analog is well known: If one plugs a guitar string and varies its length during the ring-down time, the pitch of the tone changes accordingly. This concept can be transferred to optics: Here, light is coupled into a resonator and the optical size of the latter is changed during the ring-down time. The frequency of the circulating light strictly follows the one of the varying resonance frequency. This scheme for optical frequency conversion has significant advantages over conventional methods. All intracavity photons are converted, i.e. the internal efficiency is 100 %, independent of the light intensity. This process works without taking care of phase matching, i.e. for light at all wavelengths that can circulate in the resonator. So far, only relatively small frequency shifts of the order of 100 GHz have been realized (1 nm at 1 µm wavelength). We plan to increase this value by two orders of magnitude. This shall be achieved by employing whispering gallery resonators made of potassium tantalate niobate crystals (KTN). They possess a temperature controllable transition between a ferroelectric and a paraelectric phase. Close to this phase transition, KTN crystals have extraordinarily large electro-optic coefficients. They might pave the way for a 10 % refractive-index change at electric fields of only a few kV/mm.Electro-optically driven adiabatic frequency conversion is almost unexplored. In order to achieve our ambitious goal – the realization of the abovementioned frequency converter – first, fundamental scientific questions have to be answered: What is the spatial distribution of the intracavity electric field built up by applying a voltage to the electrodes? Is there a difference between the ferroelectric and the paraelectric phases regarding the internal electric field? How close to the phase transition the system can be operated? Is there a limit for the external electric field beyond which charges are injected into the crystal? The latter might influence the internal electric field or reduce the rind-down time. In which wavelength and power range adiabatic frequency conversion can be achieved?We expect that this project will strongly inspire the scientific investigation, the technical development and the application of novel frequency converters. They might be employed for distance measurement and fast spectroscopy.

在这个项目中，我们计划实现并研究一种光学频率转换器，可将激光频率移动几个 10 THz（1 微米波长下> 50 nm）。此处，100% 的泵浦光子应在纳秒时间尺度上在单个系统中转换，适用于从可见光到中红外边缘的所有波长。频移的幅度遵循所施加的电压，使得可以通过电压调制来实现几乎任意随时间变化的频移，例如，线性频率线性调频脉冲。这应通过绝热频率转换来实现。它的声学模拟是众所周知的：如果一个人插入吉他弦并在响铃期间改变其长度，音调的音调就会相应改变。这个概念可以转移到光学领域：在这里，光被耦合到谐振器中，并且后者的光学尺寸在衰荡时间内发生变化。循环光的频率严格遵循变化的共振频率之一。这种光频率转换方案比传统方法具有显着的优势。所有腔内光子均被转换，即内部效率为 100%，与光强度无关。该过程的工作无需考虑相位匹配，即对于可以在谐振器中循环的所有波长的光。到目前为止，仅实现了 100 GHz 数量级的相对较小的频移（1 µm 波长处为 1 nm）。我们计划将该值增加两个数量级。这应通过采用由钽铌酸钾晶体 (KTN) 制成的回音壁谐振器来实现。它们具有铁电相和顺电相之间的温度可控转变。接近此相变时，KTN 晶体具有非常大的电光系数。它们可能为在只有几 kV/mm 的电场下 10% 的折射率变化铺平道路。光电驱动的绝热频率转换几乎尚未被探索。为了实现我们的宏伟目标——实现上述变频器——首先必须回答基本的科学问题：通过向电极施加电压而建立的腔内电场的空间分布是什么？关于内部电场，铁电相和顺电相之间有区别吗？系统可以在接近相变的情况下运行吗？外部电场是否存在限制，超过该限制，电荷就会注入晶体？后者可能会影响内部电场或减少冲洗时间。在哪些波长和功率范围内可以实现绝热变频？我们期望该项目能够对新型变频器的科学研究、技术开发和应用产生强烈的启发。它们可用于距离测量和快速光谱学。