Coherent pulse propagation and modelocking in terahertz quantum cascade lasers

太赫兹量子级联激光器中的相干脉冲传播和锁模

• 批准号: EP/T034246/1
• 负责人: Paul Dean
• 金额: $ 143.65万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT034246%2F1
• 关键词: Coherent; pulse; propagation; modelocking; terahertz

The generation of ultrafast and intense light pulses is an underpinning technology across the electromagnetic spectrum enabling time-resolved measurements, nonlinear photonics, coherent control of matter, and frequency comb synthesis for high-precision metrology and spectroscopy. Yet in the terahertz (THz) region of the electromagnetic spectrum (~0.5-5THz), which spans the frequency range between microwaves and the mid-infrared, a compact semiconductor-based technology platform for intense and ultrafast pulse generation has yet to be realised. Established pulse generation schemes, based on excitation of photoconductive emitters or nonlinear crystals using bulky and expensive near-infrared lasers systems, offer only low frequency modulation, or broadband emission with little control of the spectral bandwidth and pulse width. These limitations are significantly hindering the development of the THz field not only in the UK but internationally, with adverse consequences for both fundamental scientific research and the development of future applications in metrology, materials analysis and molecular spectroscopy, and ultra-high speed THz communications.One promising solution to closing this technological gap is the THz frequency quantum cascade laser (QCL) - a compact and high-power semiconductor laser based on a quantum-engineered semiconductor superlattice. However, modelocking these sources is inherently difficult to achieve due to the very fast gain recovery time in these structures. Indeed, active modelocking approaches adopted to date have succeeded only in achieving pulse widths down to ~4ps, and only low output powers are possible.In this programme we will explore a radically new approach to pulse generation in lasers, based on the phenomenon of self-induced transparency in which pulses of the correct energy and pulse duration propagate without loss in the laser cavity whilst the growth of continuous waves is supressed. Although this concept has been discussed since the 1960s, the observation of this effect in semiconductor devices has remained elusive owing to the typically short coherence times of inter-band laser transitions. QCLs, however, are the ideal tool to realize SIT-modelocking owing to their large dipole moments, relatively long inter-subband coherence times, and, importantly, the possibility of combining resonant gain and absorbing periods with engineered dipole moments.We will explore the coherent interaction of intense, ultrafast THz pulses with intersubband semiconductor heterostructures and THz QCL devices for the first time. Although these measurements are of fundamental interest in their own right, the investigation of such systems will lead to the development of the first modelocked semiconductor laser exploiting self-induced transparency. Through this approach, we will bring about a step change in QCL modelocked technology and develop THz QCLs into a foundational, compact semiconductor technology for generating intense and ultrafast THz pulses, with inherent advantages of high powers, broad spectral coverage and the ability to electrically-control the emission properties. This will pave the way for the application of modelocked THz QCLs across a wide range of areas of academic and industrial relevance, including non-linear THz science, quantum optics, ultra-high-speed THz communications, and high-precision metrology and molecular spectroscopy. But that is not all. We will also demonstrate proof-of-principle applications of these new QCL sources for molecular spectroscopy, leading to a compact, all-solid-state and electrically-controlled multi-heterodyne THz spectrometer offering >500 GHz spectral coverage and sub-millisecond acquisition times. Through this goal we will translate to the THz region the unequalled combination of broad spectral coverage, high detection sensitivity, narrow spectral resolution and fast acquisition enabled by laser frequency combs at mid- and near-infrared frequencies.

超快和强光脉冲的产生是跨电磁频谱的基础技术，可实现时间分辨测量，非线性光子学，物质的相干控制以及用于高精确度量和光谱的频率梳子合成。然而，在电磁光谱的Terahertz（THz）区域（〜0.5-5THz），该区域跨越微波和中红外之间的频率范围，尚未实现基于紧凑的半导体技术平台的紧凑半导体技术平台。建立的脉冲产生方案基于使用笨重且昂贵的近红外激光系统对光电传射器或非线性晶体的激发，仅提供低频调制或宽带发射，几乎无法控制光谱带宽和脉冲宽度。这些限制极大地阻碍了THZ领域的发展，不仅在英国而且在国际上，对基本科学研究以及未来在计量学，材料分析和分子光谱的发展以及超高速度THZ通信的发展产生了不利的后果。基于量子工程的半导体超晶格。但是，由于这些结构中的恢复时间非常快，对这些来源进行模型本质上很难实现。 Indeed, active modelocking approaches adopted to date have succeeded only in achieving pulse widths down to ~4ps, and only low output powers are possible.In this programme we will explore a radically new approach to pulse generation in lasers, based on the phenomenon of self-induced transparency in which pulses of the correct energy and pulse duration propagate without loss in the laser cavity whilst the growth of continuous waves is supressed.尽管自1960年代以来就已经讨论过这个概念，但由于典型的频段间激光跃迁的相干时间很短，因此在半导体设备中观察到这种效果仍然难以捉摸。但是，QCL是由于其较大的偶极矩，相对较长的较长的寄生带相干时间，以及重要的是，将谐振增益和吸收时期与工程偶极时矩相结合的可能性。 时间。尽管这些测量值本身具有基本兴趣，但对这种系统的调查将导致开发第一个模型的半导体激光器，从而利用自我诱导的透明度。通过这种方法，我们将使QCL模型岩石技术的逐步变化，并将THZ QCLS开发为基础，紧凑的半导体技术，以产生强烈和超快的THZ脉冲，具有高功率，广泛的光谱覆盖范围的固有优势，并具有电力控制发射特性的能力。这将为在多个学术和工业相关性领域中应用模型的THZ QCL铺平道路，包括非线性THZ科学，量子光学，超高速度THZ通信以及高精度计量学和分子光谱学。但这不是全部。我们还将展示这些新QCL源用于分子光谱法的原则证明，从而导致紧凑，全固定状态和电控制的多脱螺旋thz光谱仪> 500 GHz光谱覆盖范围> 500 GHz光谱覆盖范围和亚毫米次获得时间。通过这个目标，我们将转化为THZ区域，即广泛的光谱覆盖率，高检测灵敏度，狭窄的光谱分辨率和快速采集的组合，并由激光频率梳子在中和近红外频率下实现。

项目成果

Sub-surface damage detection in marble structures using THz time domain and laser feedback interferometric imaging techniques

使用太赫兹时域和激光反馈干涉成像技术检测大理石结构的次表面损伤

• DOI: 10.1117/12.2592548
• 发表时间: 2021
• 作者: Bandyopadhyay A

Terahertz imaging with self-pulsations in quantum cascade lasers under optical feedback

• DOI: 10.1063/5.0056487
• 发表时间: 2021-09-01
• 期刊: APL PHOTONICS
• 影响因子: 5.6
• 作者: Qi, Xiaoqiong;Bertling, Karl;Rakic, Aleksandar D. D.
• 通讯作者: Rakic, Aleksandar D. D.

Observation of optical feedback dynamics in single-mode terahertz quantum cascade lasers: Transient instabilities

• DOI: 10.1103/physreva.103.033504
• 发表时间: 2021-03-08
• 期刊: PHYSICAL REVIEW A
• 影响因子: 2.9
• 作者: Qi, Xiaoqiong;Bertling, Karl;Rakic, Aleksandar D.
• 通讯作者: Rakic, Aleksandar D.

Terahertz imaging of human skin pathologies using laser feedback interferometry with quantum cascade lasers.

• DOI: 10.1364/boe.480615
• 发表时间: 2023-04-01
• 期刊: BIOMEDICAL OPTICS EXPRESS
• 影响因子: 3.4
• 作者: Qi, Xiaoqiong;Bertling, Karl;Stark, Mitchell S.;Taimre, Thomas;Kao, Yung-Ching;Lim, Yah Leng;Han, She;O'Brien, Blake;Collins, Angus;Walsh, Michael;Torniainen, Jari;Gillespie, Timothy;Donose, Bogdan C.;Dean, Paul;Li, Lian He;Linfield, Edmund H.;Davies, A. Giles;Indjin, Dragan;Soyer, H. Peter;Rakic, Aleksandar D.
• 通讯作者: Rakic, Aleksandar D.

Prospects of temperature performance enhancement through higher resonant phonon transition designs in GaAs-based terahertz quantum-cascade lasers

通过砷化镓基太赫兹量子级联激光器中更高谐振声子跃迁设计提高温度性能的前景

• DOI: 10.1088/1367-2630/ac5b41
• 发表时间: 2022
• 期刊: New Journal of Physics
• 影响因子: 3.3
• 作者: Demic A