超宽带MIR移动目标探测技术初探

针对一种基于超宽带的MIR移动目标探测中的关键技术基于阶跃二极管的微功率超宽带脉冲产生、“对称振子”超宽带天线以及超宽带的“相关检测”电路的实现进行了较为详细的论述;应用该技术对不同材质移动目标进行了定性分析和探测实验达到预期效果。

激光入射角对干涉带通滤光片输出性能的影响

利用红外光谱分析技术,研究了激光入射角度对干涉带通滤光片输出性能的影响。激光入射角的变化对滤光片的峰值波长、峰值透过率等性能参数具有明显的影响;分析了中红外滤光片对3.8μm波段激光的透射性能,给出了滤光片的输出特性与入射激光角度的变化关系。

基于黑体源和带通滤光片的中红外探测器响应率测量方法

为实现探测器响应率测量中辐射源的稳定红外辐射,利用高温黑体和干涉带通滤光片组合的方法得到了3.8μm中红外辐射,测量了HgCdTe中红外探测器的室温响应率。结果表明,通过上述组合方法获得了均匀的远场窄带红外辐射,可用于精确测量探测器在不同波段的响应率;分析了黑体源温度、干涉滤光片带宽和辐射距离对光功率密度的影响,并通过与其他标定光源的比对,验证了该方法的有效性。

利用域排列算法设计铌酸锂晶体实现3μm中红外波段频域纯态单光子源

中红外波段的单光子源对于下一代量子传感、量子通信和量子成像的研究非常重要.目前常用的产生中红外单光子源的方法是基于周期极化铌酸锂(periodically poled lithium niobate,PPLN)自发参量下转换过程.但是,基于普通PPLN制备的单光子源频域纯度不高,最高值只有0.82左右,会影响量子信息处理方案的保真度.本文利用域设计理论对30 mm长铌酸锂晶体的4000个域进行了定制化排列,消除了相位匹配函数中的旁瓣,获得了高斯型的分布.计算得到的单光子源的频域纯度可达0.99,可调谐范围为2.7—3.3μm.该定制极化铌酸锂(customized poled lithium niobate,CPLN)有望为中红外波段量子信息研究提供性能优异的单光子光源.

Silicon photonic platforms for mid-infrared applications [Invited]

Silicon photonic integrated circuits for telecommunication and data centers have been well studied in the past decade, and now most related efforts have been progressing toward commercialization. Scaling up the silicon-oninsulator(SOI)-based device dimensions in order to extend the operation wavelength to the short mid-infrared(MIR) range(2–4 μm) is attracting research interest, owing to the host of potential applications in lab-on-chip sensors, free space communications, and much more. Other material systems and technology platforms, including silicon-on-silicon nitride, germanium-on-silicon, germanium-on-SOI, germanium-on-silicon nitride, sapphireon-silicon, Si Ge alloy-on-silicon, and aluminum nitride-on-insulator are explored as well in order to realize low-loss waveguide devices for different MIR wavelengths. In this paper, we will comprehensively review silicon photonics for MIR applications, with regard to the state-of-the-art achievements from various device demonstrations in different material platforms by various groups. We will then introduce in detail of our institute's research and development efforts on the MIR photonic platforms as one case study. Meanwhile, we will discuss the integration schemes along with remaining challenges in devices(e.g., light source) and integration. A few application-oriented examples will be examined to illustrate the issues needing a critical solution toward the final production path(e.g., gas sensors). Finally, we will provide our assessment of the outlook of potential futureresearch topics and engineering challenges along with opportunities.

Tm^(3+) and Nd^(3+) singly doped LiYF_4 single crystals with 3-5 μm mid-infrared luminescence

Mid-infrared（MIR） emissions of 2.4 and 3.5 μm from Tm3＋：LiYF4 single crystals attributed to3H4 →3H5 and3H5 →3F4 transitions as well as MIR emissions of 4.2,4.3,and 4.5 μm from Nd3＋：LiYF4 lasers attributed to4I15/2 →4I13/2,4I13/2 →4I11/2,and4I11/2 →4I9/2 transitions,respectively,are observed.LiYF4 single crystals possess high transmittance of over 85% in the 2.5-6 μm range.The large emission crosssections of Tm-doped crystals at 2.4 μm（1.9×10-20cm2） and Nd-doped crystals at 4.2 μm（0.84×10-20 cm2） as well as the high rare-earth doping concentrations,excellent optical transmission,and chemicalphysical properties of the resultant samples indicate that Nd3＋and Tm3＋singly doped crystals may be promising materials for application in MIR lasers.

Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

We present the numerical results for the optimization of the pump-to-idler conversion efficiencies of nanosecond idler wavelength tunable cascaded optical parametric oscillators （OPO） in different wavelength tuning ranges, where the primary signals from the OPO process are recycled to enhance the pump-to-idler conversion efficiencies via the simultaneous dif- ference frequency generation （DFG） process by monolithic aperiodically poled, magnesium oxide doped lithium niobate （APMgLN） crystals. The APMgLN crystals are designed with different chirp parameters for the DFG process to broaden their thermal acceptance bandwidths to different extents. The idler wavelength tuning of the cascaded OPO is realized by changing the temperature of the designed APMgLN crystal and the cascaded oscillation is achieved in a single pump pass singly resonant linear cavity. The pump-to-idler conversion efficiencies with respect to the pump pulse duration and ratio of OPO coefficient to DFG coefficient are calculated by numerically solving the coupled wave equations. The optimal work- ing conditions of the tunable cascaded OPOs pumped by pulses with energies of 350 p_J and 700 ~J are compared to obtain the general rules of optimization. It is concluded that the optimization becomes the interplay between the ratio of OPO coefficient to DFG coefficient and the pump pulse duration when the idler wavelength tuning range and the pump pulse energy are fixed. Besides, higher pump pulse energy is beneficial for reaching higher optimal pump-to-idler conversion efficiency as long as the APMgLN crystal is optimized according to this pump condition. To the best of our knowledge, this is the first numerical analysis of idler wavelength tunable cascaded OPOs based on chirp-assisted APMgLN crystals.

The quantized chemical reaction resonantly driven by multiple MIR-photons:From nature to the artificial

Biochemical reactions in vivo occur at the temperature usually lower than that in vitro,however the underlying mechanism still remains a challenge.Inspired by our recent studies of adenosine triphosphate(ATP)releasing photons to resonantly drive DNA replication in a quantum way,we propose a quantized chemical reaction driven by multiple mid-infrared(MIR)photons.The space confinement effect of enzymes on a reactant molecule increases the lifetime of excitation state of its bond vibration,providing a chance for the bond to resonantly absorb multiple photons.Although the energy of each MIR photon is significantly lower than that of chemical bond,the resonant absorption of multiple photons can break the appointed bond of confined molecules.Different from the traditional thermochemistry and photochemistry,the quantized chemical reactions could have a high energy efficiency and ultrahigh selectivity.In addition,we also suggest a quantum driving source for our quantum-confined superfluid reactions proposed previously.The quantized chemical reaction resonantly driven by multiple MIR photons holds great promise to develop novel approaches for the chemical engineering in future.