Nonlinear semiconductor superlattices for the Gigahertz to the Mid Infrared ranges

The generation of high power coherent radiation in the GHz to THz ranges is a very important topic of recent research, notably after recent findings that synchronization between superlattices leads to a dramatic increase in... [ view full abstract ]

The generation of high power coherent radiation in the GHz to THz ranges is a very important topic of recent research, notably after recent findings that synchronization between superlattices leads to a dramatic increase in output power [1]. Nonlinear optical effects in semiconductor materials have been strongly investigated in the near infrared and visible spectra, but the GHz-THz-Mid Infrared (MIR) ranges are wide open for investigation.  

This talk starts with a fully predictive microscopic approach combining Nonequilibrium Green's Functions and relaxation-rate approximations for the Boltzmann equation describing the nonlinear polarization in semiconductor superlattices (SSLs) at arbitrary orders in very good agreement with experiments [2,3].

Next we investigate the ultimate efficiency of SSLs as devices [4]  for room temperature THz emission based on harmonic on multiplication of GHz inputs including limitations imposed by the buildup of electric field domains [5].

These results open the possibility of extending the whole field of nonlinear optics to the GHZ-THz range and the possibility of designing materials and devices for a large number of applications, including spectroscopy of biomolecules, which typically have strong GHz-THz resonances.

References:  

[1] B. Gaifullin et al, Phys. Rev. Applied 7, 044024 (2017).

[2] M.F. Pereira et al, Phys. Rev. B 96, 045306 (2017).

[3] M.F. Pereira et al, Nanophoton 11 (4), 046022 (2017).

[4] Karl F. Renk et al, Advances in Optoelectronics, 54042 (2007).

[5] K. N. Alekseev, et al, EPL (Europhysics Letters), 73(6):934, 2006.

Figure Captions:

Fig.1.  Normalized Harmonic Power  of  the l^th harmonic to the 3^rd harmonic  nonlinearly generated by input fields oscillating. The corresponding solid lines have been calculated using our theory.

Fig. 2. Calculated efficiency for a  (3 X ω₁=300 GHz) parametric oscillator as a function of the pump amplitude U₁. The amplitude of the third harmonic is fixed at U₃=0.1U_c. The dark grey region indicates the response of efficiency if ones assumes that electric instability (domains) at large pump amplitudes does not prevent the field in the resonator from growing.