Abstract-Negative terahertz conductivity and amplification of surface plasmons in graphene–black phosphorus injection laser heterostructures

V. Ryzhii, T. Otsuji, M. Ryzhii, A. A. Dubinov, V. Ya. Aleshkin, V. E. Karasik, and M. S. Shur

https://journals.aps.org/prb/accepted/9b078O08Pf81783789dd94946bdb6e0d63736de90

We propose and evaluate the heterostructure based on the graphene-layer (GL) with the lateral electron injection from the side contacts and the hole vertical injection via the black phosphorus layer (PL) (p${}^{+}$P-PL-GL heterostructure). Due to a relatively small energy of the holes injected from the PL into the GL (about 100 meV, smaller than the energy of optical phonons in the GL which is about 200 meV), the hole injection can effectively cool down the two-dimensional electron-hole plasma in the GL. This simplifies the realization of the interband population inversion and the achievement of the negative dynamic conductivity in the terahertz (THz) frequency range enabling the amplification of the surface plasmon modes. The later can lead to the plasmon lasing. The conversion of the plasmons into the output radiation can be used for a new types of the THz sources.

Abstract-Current-injection terahertz lasing in a distributed-feedback dual-gate graphene-channel transistor

G. Tamamushi,  T. Watanabe,  J. Mitsushio,  A. A. Dubinov,  A. Satou, T. Suemitsu,  M. Ryzhii,  V. Ryzhii,  T. Otsuji

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10111/1011126/Current-injection-terahertz-lasing-in-a-distributed-feedback-dual-gate/10.1117/12.2249983.pdf?SSO=1

This paper reviews recent advancement on the research toward graphene-based terahertz (THz) lasers. Optical and/or injection pumping of graphene can enable negative-dynamic conductivity in the THz spectral range, which may lead to new types of THz lasers. A forward-biased graphene structure with a lateral p-i-n junction was implemented in a distributed-feedback (DFB) dual-gate graphene-channel FET and observed a single mode emission at 5.2 THz at 100K. The observed spectral linewidth fairly agrees with the modal gain analysis based on DFB-Fabry-Perrot hybrid-cavitymode modeling. Although the results obtained are still preliminary level, the observed emission could be interpreted as THz lasing in population-inverted graphene by carrier-injection.

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Abstract-Injection terahertz laser using the resonant inter-layer radiative transitions in double-graphene-layer structure

V. Ryzhii, A. A. Dubinov, V. Ya. Aleshkin, M. Ryzhii, T. Otsuji

http://arxiv.org/abs/1309.2724

We propose and substantiate the concept of terahertz (THz) laser enabled by the resonant electron radiative transitions between graphene layers (GLs) in double-GL structures. We estimate the THz gain for TM-mode exhibiting very low Drude absorption in GLs and show that the gain can exceed the losses in metal-metal waveguides at the low end of the THz range. The spectrum of the emitted photons can be tuned by the applied voltage. A weak temperature dependence of the THz gain promotes an effective operation at room temperature.