cw Terahertz: Phase Modulation Package

: Standard Package (green) and Phase Modulation Package (red).

Fast and accurate modulation of the terahertz phase
Twin fiber stretcher with piezo actuators
Enhanced thermal stability due to dual-fiber concept
Requires Standard Package and Spectrosc. Extension
Combination with High Power Extension recommended

cw terahertz spectroscopy based on photomixing offers the attractive feature of detecting both amplitude and phase of the terahertz wave. Determining the phase requires a modulation of the optical path length, or the terahertz frequency.
The Phase Modulation Package offers a particularly fast and accurate technique to scan the terahertz phase, by using a symmetric setup with two fiber stretchers wound around piezo actuators.

Technical Information

Specifications:

Wavelength range	853 + 855 nm	1546 + 1550 nm
Concept	Twin fiber stretcher with piezo actuators
Fibers	2 x 60 m, SM/PM fibers
Max. path length modulation	3 mm @ 1 kHz
HV driver	Included
Software	Included, part of control program

Terahertz photocurrent, using either a fiber stretcher (red circles) or a mechanical delay stage in the terahertz path (black squares). The delay-stage scan shows small deviations from a cosine fit (solid black line) due to standing waves in the terahertz path. By contrast, the fiber-stretcher scan yields a perfect cosine curve (solid red line).