Determination of refractive index and thickness of a multilayer structure with a single terahertz time domain spectroscopy measurement.

A processing technique for the determination of the average refractive index and thickness of a two-layer system is presented. It is based on a single measurement with a standard terahertz time-domain spectrometer and the multilayer system thickness. The technique relies on the interference caused by the main pulse with the echoes produced in each material. This approach allows noninvasive inspection of double-layer compound products.

Birefringence measurement in the terahertz range based on double Fourier analysis.

A method for obtaining the average refractive indexes of a birefringent material in the terahertz region in a single measurement with a standard terahertz time-domain spectrometer is presented. The method is based on processing the frequency-domain interference between terahertz pulses and echoes through the Fourier transform of the terahertz spectrum. The technique also allows the determination of the optical axis orientation of the material by making two measurements with different angles of the sample optical axis.

Terahertz radiation shaping based on optical spectrum modulation in the time domain.

A terahertz shaping system based on optical fiber components as opposed to traditional free-space solutions is proposed. It is based on the time-domain modulation of the optical source spectrum. Standard single-mode fiber distributes and disperses the pulse before filtering its spectral components by means of the cross-gain and cross-phase modulation effects taking place in an interferometric semiconductor optical amplifier structure. Experimental measurements are obtained, showing the tunability of the system as well as its reconfigurability.