Processing math: 100%
Hao Li - IEEE Xplore Author Profile

Showing 1-12 of 12 results

Filter Results

Show

Results

THz-mid infrared electric-dipole radiation resonating with longitudinal optical (LO) phonon energy is obtained from metal-semiconductor surface microstructures by heating samples for various types of semiconductors. The structures using undoped GaAs yield emission peaked at 8.5 THz. The emission properties depending on structural parameters are consistent to the electric dipole properties. The emi...Show More
Longitudinal optical (LO) phonon resonant THz absorption and emission are observed using metal-semiconductor surface stripe structures, where electric dipoles are induced by interface polarization charges. The emission spectrum is affected by the stripe structures, while the peak position is independent. Further, quantum interference of two LO phonon modes and electronic intervalence band transiti...Show More
Deep levels in GaN have been discussed so far, while phonon dynamics or thermal properties at point defects or complexes remain unclear. In most of articles, the photoluminescence analyses have been conducted using the excitation laser with greater photon energy than energy gap, while the carrier energy relaxation distorts the spectrum and intensity decay characteristics. In this report, we show t...Show More
Since heat generation in electronic devices induces the degradation of performance, the understanding of their thermal properties is required. InGaN and AlInN alloys are possibly the key materials for optical devices in green gap and high power transistors. Characteristic properties of local strain, fluctuation of energy gap, carrier dynamics, and so forth due to spatial nonuniformity of alloy com...Show More
Room temperature diffusive spin dynamics in 10 nm wide InGaAs/InAlAs quantum wells are investigated using time-resolved optical Kerr rotation microscopy in 1.5\ \mu \mathrm{m} range. Spin precession arising from spin-orbit (SO) magnetic fields were measured by scanning relative positions between pump and probe spot at the transient regime that appears before the helical spin mode. Frequency feat...Show More
THz pulse generation for the obliquely crossed optical pump pulses in optical rectification based on the lithium niobate crystal is simulated by finite-difference time-domain method. The beam diameter dependence clearly shows that Cherenkov type radiation with the broad band spectrum is dominant for the beam diameter smaller than 10 μm, while the non-collinear phase matching with narrow spectrum i...Show More
We succeeded in simultaneous two-color laser oscillation from a GaAs/AlGaAs coupled multilayer cavity by current injection at room temperature. The simultaneous lasing was confirmed by detecting SFG generated by the two color laser lights.Show More
Electro-magnetic Induced Transparency (EIT) has been studied as a mechanism of lasers without population inversion. Little attention has been given to EIT on phonon systems, while it has a potential of application to EIT and thus THz laser and modulator. Quantum interference of multiple longitudinal optical (LO) phonon modes and the continuum of inter-valence band transition is studied in this rep...Show More
Quantum interference between two LO phonon modes and valence band states is investigated by Raman spectra of p-type Ga0.5In0.5P. The spectrum fitting analysis reveals the quantum interference features in asymmetric line shape, broadening, and peak shift. This finding suggests the possibility of the control of the absorption profile in THz frequency region.Show More
Interaction of a semiconductor surface or interface and p-polarized infrared light has been investigated from the viewpoint of THz application. In this study the electric dipole absorption at the resonant energy to a longitudinal optical phonon is clearly observed also for s-polarization for lateral Ti/GaN/Ti and Ti/GaAs/Ti stripe structures. Modification of permittivity is found by the analysis o...Show More
Temporal terahertz waveforms generated from GaAs/AlAs coupled multilayer cavity structures were simulated and compared with experimental results. Femtosecond laser pulses covering two cavity-mode frequencies were used for the difference frequency generation (DFG) in the terahertz region. The Fourier components dependent on the frequency and spatial position were determined for the second-order non...Show More