Phase Modulation Extension

Phase modulation for TeraScan or TeraBeam

Resolution booster
Phase and amplitude information at any frequency
Enhanced thermal stability due to dual-fiber concept
Path length modulation up to 3 mm @ 1 kHz
Requires TeraScan or TeraBeam

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. Users can thus retrieve full information on phase and amplitude of the terahertz wave - with single-Megahertz resolution!

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Specifications

Specifications	THz Phase Mod / NIR	THz Phase Mode / IR
Concept	Twin fiber stretcher with piezo actuators
Wavelength	780 nm, as defined by TeraScan 780 / TeraBeam 780	1.5 µm, as defined by TeraScan 1550 / TeraBeam 1550

Additional Information

Schematic of TeraScan (green) with Phase Modulation Extension (red).

Terahertz photocurrent, measured with fiber stretchers (red circles) or a mechanical delay stage in the terahertz path (black squares). The delay-stage scan deviates from a cosine fit due to standing waves. The fiber-stretcher scan yields a perfect cosine curve.
Applications
- Plastic Inspection
- Paint and coating layers
- Paper quality control
- Hydration monitoring
- Communication
- Ultrafast dynamics
- Gas sensing
- Fundamental physics
Downloads
- Product Brochure Terahertz Systems
Literature
- Scientific Paper: Deninger, A., et al., 2.75 THz tuning with a triple-DFB laser system at 1550 nm and InGaAs photomixers, J. Infr. THz Waves (2015)
- Scientific Paper: Roggenbruck, A., et al., Using a fiber stretcher as a fast phase modulator in a continuous wave terahertz spectrometer, J. Opt. Soc. Am. B (2012)
- Scientific Paper: Stanze, D., et al., Compact cw Terahertz Spectrometer Pumped at 1.5 µm Wavelength, J Infrared Milli Terahz Waves (2010)
- Scientific Paper: Roggenbruck, A., et al., Coherent broadband continuous-wave terahertz spectroscopy on solid-state samples, New Journal of Physics (2010)
- Scientific Paper: Deninger, A., et al., Precisely tunable continuous-wave terahertz source with interferometric frequency control, Rev. Sci. Instrum. (2008)
- Overview Article: Lang, M., et al., Laser-based terahertz generation & applications, Photonik International (2012)
Related Products
- TeraScan: Complete cw-terahertz spectroscopy platform
- TeraBeam: Dual-color DFB lasers with digital driver electronics
- Phase Modulation Extension: Twin fiber stretcher
- Photomixers: Packaged modules with fiber pigtail
- Accessories: Schottky diodes and optomechanics
- TeraFlash: Time-domain terahertz platform

Difference frequency tuning	See TeraScan / TeraBeam systems
Difference frequency resolution	See TeraScan / TeraBeam systems Complete amplitude + phase information available at maximum resolution.
Fibers	2 x 60 m, SM/PM fibers
Max. path length	3 mm @ 1 kHz
HV amplifier	Included
Software	Included, part of control programm