Active photonic crystal terahertz laser

Abstract

We present the design and the realization of active photonic crystal (PhC) semiconductor lasers. The PhC consists of semiconductor nanostructure pillars which provide gain at a quantized transition energy. The vertical layer sequence is that of a terahertz quantum cascade laser. Thereby, the artificial crystal itself provides the optical gain and the lateral confinement. The cavities do not rely on a central defect, the lasing is observed in flat-band regions at high symmetry points. The experimental results are in excellent agreement with the finite-difference time-domain simulations. For the vertical confinement a double-metal waveguide is used. The lasers are showing a stable single-mode emission under all driving conditions. Varying the period of the PhC allows to tune the frequency by 400 GHz.

Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

“…11 In this Letter, we investigate device architectures that can provide high (tens of milliwatt) CW output powers. Specifically, we aim to obtain significantly higher powers than have been observed to date using either 2D photonic crystals [12][13][14][15][16][17][18] or second-order DFB gratings. [19][20][21][22][23][24] Recently, we have demonstrated surface-emitting THz QCLs based on graded photonic heterostructure (GPH) resonators (shown schematically in Fig.…”

Photonic crystal mode terahertz lasers

“…The broad gain region of the active region of terahertz-QCLs allows to shift the emission frequency in a wide range using the same active region. 10,11 We are going to show the use of 2D-PhC with complete TM bandgaps for the emission frequency control of terahertz-QCLs. The devices are based on PhC-mirrors that surround a central gain region.…”

Influence of the facet type on the performance of terahertz quantum cascade lasers with double-metal waveguides

“…The best performing THz QCLs, in terms of maximum operation temperature, have been achieved by employing double-metal waveguides, 5 where the active region is sandwiched between a top and bottom metal layer. In this way, various resonator types can be fabricated, like disks, 6 photonic crystals, 7 and meta-materials. 8 For ridge resonators, commonly used for semiconductor lasers, the facet is typically fabricated by cleaving the structure, thus the top and bottom contact layers are terminated at the edge of the resonator on top of each other.…”