Wavelength conversion through plasmon-coupled surface states

Abstract

Surface states generally degrade semiconductor device performance by raising the charge injection barrier height, introducing localized trap states, inducing surface leakage current, and altering the electric potential. We show that the giant built-in electric field created by the surface states can be harnessed to enable passive wavelength conversion without utilizing any nonlinear optical phenomena. Photo-excited surface plasmons are coupled to the surface states to generate an electron gas, which is routed to a nanoantenna array through the giant electric field created by the surface states. The induced current on the nanoantennas, which contains mixing product of different optical frequency components, generates radiation at the beat frequencies of the incident photons. We utilize the functionalities of plasmon-coupled surface states to demonstrate passive wavelength conversion of nanojoule optical pulses at a 1550 nm center wavelength to terahertz regime with efficiencies that exceed nonlinear optical methods by 4-orders of magnitude.

Coherent terahertz radiation with 2.8-octave tunability through chip-scale photomixed microresonator optical parametric oscillation

“…With the designed cavity mode dispersion and differential TE-TM thermal dependence, the tunable OPO is facilitated by gradually changing the pump-resonance detuning, where the optical power absorption leads to increase (decrease) of the resonant mode temperature by forward (backward) pump wavelength tuning. The generated tunable OPO is passively down-converted to the terahertz radiation via a plasmonic nanoantenna array built on the InAs substrate 53 . The incident optical beam excites surface plasmons on the nanoantenna array, providing strong enhancement of the generated near-field photocarriers, subsequently accelerated by the surface built-in electric field in the InAs substrate without any external bias voltage.…”

Magnetic Field‐Assisted Laser Shock Peening of Ti6Al4V Alloy

“…The range of deviation reduces by 22.85% after PMT due to the depinning effects of the pulsed magnetic field (Figure 3b). [28,38] For the MFLSPed sample, the deviation range is constant, and hardness values at each indentation point increase by %20 HV. Without PMT, hardness values at each indentation point increase by %5 HV with a large deviation range of 48.89 HV on the FLSPed surface.…”

Terahertz interface physics: from terahertz wave propagation to terahertz wave generation

“…Currently, there are four methods to generate a strong THz electric field with a strength of up to the MV cm −1 scale: (a) optical rectification from nonlinear crystal, such as ferroelectric crystal [162], semiconductor crystal [163], and organic crystal [164]; (b) photoinduced plasma from air [165] and solid foil [166]; (c) transition radiation of ultrafast electron bunches at discontinuous interfaces [167]; (d) spin-related magnetic interfaces [168]. THz electric field strength can be further enhanced by the combination of air and transparent dielectric materials [169] or by coupling between plasma and surface state at an interface [170]. We will mainly focus on THz wave generation at interfaces in the following part of this review.…”