VT VT Vinh Nguyen Group

Contact information:

Department of Physics
Virginia Tech, MC 0435
Blacksburg, VA 24061
Tel: (540) 231-3158
Fax: (540) 231-7511


Vector Newtwork Analyzer

The PNA network analyzer is the world´s most integrated and flexible single-connection microwave test engine for measuring active devices such as amplifiers, mixers, and frequency converters. The system provides unrivalled configurability with a built-in second source, combiner, and internal signal-routing switches.

PNA N5225A
Agilent Vector Network Annayzer (PNA N5225A)

Key Features & Specifications:
• 10 MHz to 50 GHz
• 4-ports with two built-in sources
• 126 dB system and 129 receiver dynamic range, 32,001 points, 32 channels, 5 MHz IF bandwidth
• High output power (+16 dBm), low harmonics (-60 dBc) and a wide power sweep range (41 dB)
• Best dynamic accuracy: 0.1 dB compression with +15 dBm input power at the receiver
• Low noise floor of -111 dBm at 10 Hz IF bandwidth

For more details on the quite extraordinary specifications of this piece of equipment, please visit the manufacturers product page.

Dielectric Probe

The Agilent 85070E Dielectric Probe Kit, used with an Agilent network analyzer, determines the intrinsic electromagnetic properties of many dielectric materials. Because these properties are determined by the molecular structure, they can be related to other properties of interest as well. Measuring them can provide critical insight to applications in many industries.

The 85070E (slim form) has a frequency range of 500 MHz to 50 GHz and is useful in all stages of a product's lifecycle: design, incoming inspection, process monitoring, and quality assurance. For example, it can provide important information about materials used in state-of-the-art RF and microwave electronic components. Even biomass, bulk density, bacterial content, and chemical concentration can be related to a material's electromagnetic properties.

Dielectric probe 85070E (slim form)

Dielectric probe 85070E (slim form) with Agilent Vector Network Annayzer (PNA N5225A)

VDI's Vector Network Analyzer extension modules

VDI’s VNA Extenders provide high performance frequency extension of vector network analyzers into the THz range. Our models cover frequency range from 65 GHz to 1.1 THz. These modules combine high test port power and superb dynamic range to offer unparalleled performance.

VDI's Vector Netwrok Analyzer extension modules

VDI's Vector Netwrok Analyzer extension (WR 1.0) with Agilent

Effective dynamic range of VDI's Vector Netwrok Analyzer extension modules

Spectra-Physics Mai Tai Femtosecond Laser

This product from Spectra-Physics is designed for use with a terahertz time-domain system. The Spectra-Physics® Mai Tai® VF-T1S ultrafast laser is the ultimate short-pulse oscillator with an unprecedented level of automation and long-term environmental stability. The Mai Tai VF laser is capable of producing a broad range of output bandwidths: 60 nm to 10 nm, corresponding to near transform-limited pulse widths.


Mai Tai VF-T1S Laser

• Completely automated, new one-box mode-locked Ti:Sapphire laser source.
• Tunable wavelength configuration with tuning range between 750-850nm.
• Average power output of > 1 W.
• Pulse duration is sub 60 fs.
• Low beam divergence of 1.0 mrad enables efficient transmission of laser light to sample through microscope optics.
• Features: Regenerative mode-locking, the only dropout-free mode-locking method.
• Enables wavelength scanning without losing mode-locking (zero re-optimization time).
• Integrates combination of award-winning Millennia diode-pumped solid-state laser with rugged monolithic Ti:sapphire cavity into one ultra-compact package (23x14x6 inches).
• With complete automated control and tuning, the Millennia pump-source assures superior power and tuning.
• Continuously tunable over entire range with zero drop-outs.
• Easy integration into microscope system.
• Pointing stability 1/30 of beam diameter across the tuning range. No realignment of microscope coupling optics after tuning.

Terahertz Time-Domain Spectroscopy

The Femtosecond Ti:sapphire Laser (Mai Tai VT-T1S) produces ultra-short (60 fs) optical pulses at 800 nm with a repetition rate of 80 MHz. The optical pulses are split into two parts: one used for the THz generation and the other for detection. Photoconductive antennas (TERA-K8 from Menlo systems) are used for both THz generation and detection. A delay stage is used in the detection arm in order to vary the arrival time of the signal with respect to the optical pulse used for detection. A series of parabolic mirrors are used to guide the terahertz pulses from the emitter to the sample and then to the detector. By scanning the delay line, the electric field amplitude and phase of the THz waveform can be mapped out as a function of time.

Janis Closed-Cycle Cryostat

Terahertz time-domain transmission spectroscopy

Janis Closed-Cycle Cryostat

Terahertz time-domain reflection spectroscopy

Janis Closed-Cycle Cryostat

A typical time-domain terahertz trace and the corresponding Fourier Transform, showing the power spectrum of the pulse in logarithmic scale.

Janis 10 Kelvin Closed-Cycle Optical Cryostat

The Janis 10K closed-cycle cryostat combined with an automatic temperature controller is a powerful tool for studying the properties of materials over a wide range of temperatures from 10 K to 300 K. The closed-cycle system recirculate a fixed volume of gas to provide cooling to the sample mounting stages, and no gas is added or removed during operation. A compressor is used to provide the high pressure helium gas needed for the cycle. Flexible metal gas lines deliver the compressed helium gas to the refrigerator, and return the low pressure gas to the compressor for recirculation.

Janis Closed-Cycle Cryostat

Janis 10 Kelvin Closed-Cycle Optical Cryostat

High resolution photoluminescence spectroscopy (Horiba iHR550)

The iHR550 spectrometer offers a unique combination of spectral quality, flexibility, robustness, and ease of use that makes it the ideal general-purpose spectrometer for performing spectral measurements with quality results. The resolution with exit slit is 0.025 nm with 1200 L/mm grating. The spectrometer is equipped with six gratings: 1200 L/mm (300-1200 nm); 900 L/mm (700-2100 nm); 600 L/mm (1000-2500 nm); 300 L/mm (2-6 um); 150 L/mm (4-11 um); 75 L/mm (9-20 um) to cover the wavelength range from 300 nm to 20 um. With a focal length of 0.55 m, the iHR550 is designed to deliver superb image quality for spectral measurements, and offers the ability to perform multi-track experiments with up to 20 fiber inputs.

Janis Closed-Cycle Cryostat

High resolution photoluminescence spectroscopy (Horiba iHR550)

iS50 FTIR Spectrometer

Designed to be highly flexible, the Nicolet iS50 FTIR Spectrometer can be upgraded from a simple FT-IR bench to a fully-automated multi-spectral range system that can acquire spectra from far-infrared to visible. The unit includes built-in ATR, FIR, NIR, ABX modules at the touch of a button, enabling access to these techniques without manually changing system components with the spectra range from 15 to 27,000 cm^(-1), and the spectral resolution betweer than 0.09 cm^(-1)

Janis Closed-Cycle Cryostat

iS50 FTIR Spectrometer