Nd/Y:Sc2SiO5晶体热效应补偿获得高稳定性双波长激光研究

Laser Diode (LD) pumped solid state dual-wavelength laser is crucial in developing efficient and portable THz laser source operated at room temperature.Compared with single wavelength laser operation, dual/ multi-wavelength laser operation results in two or multiple times of nonradiative transition heat and requires efficient thermal management. In our previous work, Nd/Y:Sc2SiO5 based multi-wavelength laser has been achieved. The proposal brings forward a stable dual wavelength mode locked laser technology based on thermal compensator Nd/Y:Sc2SiO5.(1) Dual wavelength laser operation is expected in Nd/Y:Sc2SiO5 gain media with disordered and multi-crystallographic sites. (2) Dual wavelength mode locked laser will be realised in Nd/Y:Sc2SiO5 crystal with broader emission band and higher gain cross section through optimization of Nd/Sc/Y ratio. (3)Sc2SiO5 crystal possessing negative refractive index along temperature changing (dn/dT = -6.3 × 10^-6 K^-1) and high thermal conductivity (κ = 7.5 W o m^-1 o K^-1) is an ideal compensator for thermal management in laser operation. Combining a nonlinear THz crystal with large second order nonlinear coefficient and low absorption at THz band, the realization of THz source is promising by developing dual-wavelength Nd/Y:Sc2SiO5 laser based on Differential Frequency Generation (DFG) technology.

LD泵浦全固态双波长锁模激光器是发展便携式THz辐射源的研究热点。相较于单波长激光，双波长或多波长激光运转会产生两倍或多倍的无辐射跃迁（"废"热），需要高效的热管理方案。在我们前期工作中采用Nd/Y:Sc2SiO5晶体初步获得多波长激光输出。在此基础上，本项目首次提出基于Nd/Y:Sc2SiO5晶体热效应补偿获得高稳定性双波长锁模激光的技术方案：（1）通过设计无序和多格位结构基质，获得近红外与可见光波段双波长激光输出；（2）通过优化Nd/Sc/Y配比，获得更宽吸收带、更宽发射带和高增益，获得双波长锁模激光输出；（3）Sc2SiO5基质具有负折射率温度系数（dn/dT=-6.3×10^-6 K^-1）和高热导率（κ=7.5 Wom^-1oK^-1）特征，是一种理想的热效应补偿增益介质，实现高效热管理。结合二阶非线性系数较大、THz 波段吸收系数低的差频晶体，推动小型高效THz辐射源的实用化。

随着LD泵浦全固态双波长锁模激光器的发展，便携式THz辐射源的研究也迎来了新的发展机遇。相较于单波长激光，双波长或多波长激光运转会产生两倍或多倍的无辐射跃迁（“废”热），需要高效的热管理方案。本研究项目通过分子设计优化激光介质，研究晶体中稀土离子的能级结构、光谱特性及高增益特性。系统研究全固态双波长激光运转，进而实现LD 泵浦全固态双波长锁模激光输出并达到稳定基模运转。结合具有较大二阶非线性系数、 THz 波段吸收系数低的差频晶体（DAST、GaSe），实现THz（3.28THz、1.64THz） 输出。