Mode-locked semiconductor heterostructure lasers integrated with multilayer graphene
28 Aug 2022-pp 1-2
TL;DR: In this article , a multilayers graphene film was integrated in the cavity of miniaturized quantum cascade laser (QCLs) to demonstrate passive mode-locking in random THz lasers and self-starting short pulse emission in broadband QCL wire lasers in 2.3-3.6 THz range.
Abstract: By integrating, with innovative photonic architectures, in the cavity of miniaturized quantum cascade lasers (QCLs) a multilayers graphene film, we demonstrate passive mode-locking in random THz lasers and self-starting short pulse emission in broadband QCL wire lasers in the 2.3-3.6 THz range.
TL;DR: The fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite pave the way to the integration of graphene-based SA with electrically pumped THz semiconductor micro-sources, providing unprecedented compactness and resolution.
Abstract: Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies. Fourier-transform infrared spectroscopy provides evidence of intraband-controlled absorption bleaching. These results pave the way to the integration of graphene-based SA with electrically pumped THz semiconductor micro-sources, with prospects for applications where excitation of specific transitions on short time scales is essential, such as time-of-flight tomography, coherent manipulation of quantum systems, time-resolved spectroscopy of gases, complex molecules and cold samples and ultra-high speed communications, providing unprecedented compactness and resolution.
TL;DR: In this article, a miniaturized terahertz frequency-comb-synthesizers (FCS) with a tightly-coupled on-chip solution-processed graphene saturable-absorber reflector is proposed.
Abstract: The ability to engineer quantum-cascade-lasers (QCLs) with ultrabroad gain spectra and with a full compensation of the group velocity dispersion, at Terahertz (THz) frequencies, is a fundamental need for devising monolithic and miniaturized optical frequency-comb-synthesizers (FCS) in the far-infrared. In a THz QCL four-wave mixing, driven by the intrinsic third-order susceptibility of the intersubband gain medium, self-lock the optical modes in phase, allowing stable comb operation, albeit over a restricted dynamic range (~ 20% of the laser operational range). Here, we engineer miniaturized THz FCSs comprising a heterogeneous THz QCL integrated with a tightly-coupled on-chip solution-processed graphene saturable-absorber reflector that preserves phase-coherence between lasing modes even when four-wave mixing no longer provides dispersion compensation. This enables a high-power (8 mW) FCS with over 90 optical modes to be demonstrated, over more than 55% of the laser operational range. Furthermore, stable injection-locking is showed, paving the way to impact a number of key applications, including high-precision tuneable broadband-spectroscopy and quantum-metrology.
TL;DR: In this paper, the key transformative applications of 2D nanomaterials for the development of nanoelectronic, nanophotonic, optical, and plasmonic devices at terahertz frequencies are discussed.
Abstract: The discovery of graphene and its fascinating capabilities has triggered an unprecedented interest in inorganic two-dimensional (2D) materials. van der Waals layered materials such as graphene, hexagonal boron nitride, transition metal dichalcogenides, and the more recently re-discovered black phosphorus (BP) indeed display an exceptional technological potential for engineering nano-electronic and nano-photonic devices and components “by design,” offering a unique platform for developing new devices with a variety of “ad hoc” properties. In this Perspective article, we provide a vision on the key transformative applications of 2D nanomaterials for the development of nanoelectronic, nanophotonic, optical, and plasmonic devices at terahertz frequencies, highlighting how the rich physical phenomena enabled by their unique band structure engineering can allow them to boost the vibrant field of quantum science and quantum technologies.