Mid-IR lasing in HgCdTe multiple quantum well edge-emitting ridges.

Thin HgCdTe/CdHgTe quantum wells (QWs) grown on alternative GaAs (013) substrates have been recently proposed as a material for coherent emitters in the mid-IR region. In this work, we develop a technological process for the fabrication of ridge microresonators in waveguide heterostructures with multiple HgCdTe QWs via photolithography and ion etching. We process two samples with different ridge heights and analyze their emission spectra measured under optical excitation. The width of the emission spectra dropped by an order of magnitude compared to the nonprocessed as-grown structure, allowing one to conclude that lasing at 9.2-7.1 µm takes place within the 8-120 K temperature range. However, both samples demonstrated faster temperature quenching of lasing than that of the single-pass stimulated emission from the nonprocessed structure, as well as a drop in the carrier lifetimes. These figures of merit are likely to be compromised not by the Q factor of the cavities, but due to defects induced during the etching process. Finally, the implications for HgCdTe-based lasers for the 3-5 µm transparency window and longer wavelengths (beyond 20 µm) are discussed.

Tuning the Luminescence Response of an Air-Hole Photonic Crystal Slab Using Etching Depth Variation.

Detailed studies of the luminescent properties of the Si-based 2D photonic crystal (PhC) slabs with air holes of various depths are reported. Ge self-assembled quantum dots served as an internal light source. It was obtained that changing the air hole depth is a powerful tool which allows tuning of the optical properties of the PhC. It was shown that increasing the depth of the holes in the PhC has complex influences on its overall photoluminescence (PL) response due to the simultaneous influences of counteracting factors. As a result, the maximal increase in the PL signal of more than two orders of magnitude was obtained for some intermediate, but not full, depth of the PhC's air holes. It was demonstrated that it is possible to engineer the PhC band structure in such a way as to construct specific states, namely bound states in continuum (BIC), with specially designed dispersion curves being relatively flat. In this case, such states manifest themselves as sharp peaks in the PL spectra, and have high Q-factors which are larger than those of radiative modes and other BIC modes without such a flat dispersion characteristic.