Nonlinear phase matching in THz semiconductor waveguides

Abstract

Waveguide phase matching of a frequency conversion process within an isotropic semiconductor is studied. The three-wave interaction involves pump and signal beams in the near infrared, and the idler at THz frequencies, i.e. with a wavelength greater than 50 µm in GaAs. Phase matching is obtained by exploiting modal dispersion and, for energies below the reststrahlen region, the semiconductor anomalous dispersion. This original phase matching scheme provides simultaneously a long interaction length, due to waveguide confinement, and efficient wave mixing because only the fundamental modes are involved in a modal phase matching process. Two different types of waveguides are studied: bulk semiconductor rods and plasmon waveguides.

Mode-Locked Dual-Wavelength Heterolasers for Terahertz Generation via Intracavity Wave Mixing

“…As an example, let us consider an Al x Ga 1−x As QW heterostructure consisting of two adjacent wells made of two 5-8 nm thin layers separated by a thin spacer (≈ 30 nm) and incorporated into a core of an AlGaAs and plasmon waveguide [6]. Further, we shall consider a simple structure with one heavy-hole (1) and two electron (2 and 3) states in the left asymmetric QW and one hole (4) and one electron (5) state in the right one, so that the transition 3 → 1 is resonant with 5 → 4 one (Fig.…”

Highly tunable Terahertz filter with magneto-optical Bragg grating formed in semiconductor-insulator-semiconductor waveguides

“…6 For these applications, THz plasmonic components based on surface plasmon polariton (SPP), such as isolators, 7 waveguides, [8][9][10] Lenses, 11 and mirrors, 12 have been proposed due to the sub-wavelength confinement for miniaturized devices.…”

Optical side-band generation in THz Fabry-Perot laser cavities

“…However, nonlinear optics in semiconductor lasers comes with two design challenges: waveguide dispersion and facet feedback. Firstly, phase matching (PM) in nonlinear processes is highly sensitive to the refractive indices experienced by the waves involved [10,11]. 30 Therefore, the combined material and waveguide dispersion of the laser cavity controls both the frequency and bandwidth of the nonlinear process.…”

“…However, by exploiting a combination of the anomalous dispersion introduced by the Reststrahlen band and modal phase matching [16], one can achieve efficient PM between THz and NIR waves (f p = f NIR , f i = f THz ) [11]. In practice, this is accomplished by integrating a NIR waveguide into the active region of the QCL, leading to a strong optical field overlap and hence high conversion efficiency [2,5,6].…”