Picometrix, Inc.

University of Rochester

University of Michigan

Luna Innovations Inc.

Steven L Williamson

David Zimdars

Gerard A Mourou

Jeffrey S White

Matthew W Warmuth

James V Rudd

Artur Chernovsky

Robert N Sacks

David A Zimdars

Janis A Valdmanis

Philippe Bado

John A Nees

Carl H Petras

Irl N Duling, Iii

Matthew M Jazwiecki

Irl Duling

Gregory D Fichter

Klaus Wolter

Timothy Strong

Gregory Stuk

Girard Mourou

Kadhair Al Hemyari

Greg Stuk

Artur A Chernovsky

Klaus H Wolter

Mathew M Jazwiecki

Gregory D Ficter

Greg Fichter

Gregg Sucha

A system for determining at least one property of a sheet dielectric sample using terahertz radiation includes at least one terahertz transmitter configured to output a pulse of terahertz radiation, a terahertz receiver configured to receive at least a portion of the pulse of terahertz radiation, wherein the terahertz receiver is configured to output a measured waveform based on the terahertz radiation received by the terahertz receiver, and a control unit in communication with the terahertz receiver. Wherein the control unit is configured to choose at least one region of interest of the measured waveform, compare the at least one region of interest of the measured waveform to a model waveform, vary at least one parameter of a model waveform to minimize the difference between the model waveform and the measured waveform.

System for determining at least one property of a sheet dielectric sample using terahertz radiation

A system for transmitting and receiving electromagnetic radiation includes a beam splitter and a transceiver. The beam splitter is configured to separate an optical pulse into a pump pulse and a probe pulse. The transceiver may include a transmitter switch and a receiver switch. The pump pulse is directed toward the transmitter switch and the probe pulse is directed towards the receiver switch. Electromagnetic radiation is emitted from the transceiver when the pump pulse strikes the transmitter switch. The electromagnetic radiation may be terahertz radiation in either a pulsed or continuous wave form.

System for transmitting and receiving electromagnetic radiation

A semiconductor structure includes a GaAs or InP substrate, an InGaAs epitaxial layer grown on the substrate, where x is greater than about 0.01 and less than about 0.53, and a wider bandgap epitaxial layer grown as a cap layer on top of the InGaAs epitaxial layer.

Photoconductive device

A system and method to measure, with increased precision, the transit time position(s) of pulses in a time domain data. An example data set would be the transit time of pulses in Time-Domain Terahertz (TD-THz) data. The precision of the pulse timing directly affects the precision of determined sample properties measurements (e.g., thickness). Additionally, an internal calibration etalon structure and algorithm method provides for continuous system precision/accuracy check method to increase sample measurement integrity. The etalon structure can improve the precision of sample property measurements (e.g., absolute thickness). Various hardware and system implementations of the above are described.

System and method to measure the transit time position(s) of pulses in time domain data

A system for varying a delay of an optical beam has a rotatable wheel and a set of one or more prisms mounted about a circumference of the rotatable wheel. The set of one or more prisms are positioned to retroreflect the optical beam that passes approximately tangent to the rotatable wheel to cause a delay or phase shift to the beam as the rotatable wheel rotates.

Optical delay

A system to detect an article includes one or more terahertz modules. Each module either generates or receives, or both generates and receives, terahertz radiation. Some of the terahertz radiation is reflected from the article and the remainder of the terahertz radiation is transmitted through the article. A processor analyzes the reflected and transmitted terahertz radiation to characterize the article.

Terahertz imaging system for examining articles

This invention is directed to a fiber attachment including a hot pad and solder glass that attaches an optical fiber to the hot pad. The attached is formed by positioning the optical fiber over the hot pad and aligning the optical fiber. The optical fiber is then raised and solder glass preforms are positioned on the hot pad. Heat is applied to the glass preforms such that they melt. Once the preforms are melted, the optical fiber is lowered into the molten solder glass. The current is then removed and the solder glass solidifies as it cools to form an attachment between the optical fiber and the hot pad.

Precision fiber attachment

The present invention is a fiber optic waveguide adapted for focusing a beam of light at an obtuse angle to the optical axis. A focusing end of the fiber optic is polished at an angle such that the surface normal does not coincide with the optical axis, which is defined by the path of the beam of light through the fiber optic waveguide. The angle &#x3b8; is necessarily greater than 0 degrees and less than 90 degrees. The present invention further includes a focusing lens coupled to the outside of the fiber optic waveguide at its focusing end. The focusing lens may be a ball lens, and it is attached to the exterior of the cladding layer by an adhesive material.

Focusing fiber optic

The present invention includes a semiconductor epitaxial structure optimized for photoconductive free space terahertz generation and detection; and amplifier circuits for photoconductively sampled terahertz detection which may employ the optimized epitaxial structures.

Amplified photoconductive gate

A system and method for using terahertz radiation to detect and monitor a substance undergoing a change in phase from a liquid phase to a solid phase or vice-versa is disclosed. By employing terahertz radiation in either the pulsed mode or in the continuous-wave (CW) mode, the system can non-invasively monitor these changes. The system uses the principle that matter in a liquid state will absorb and attenuate terahertz radiation to a larger degree than matter in a semisolid or solid state. Most terahertz radiation absorption occurs due to the rotational motions of molecules, i.e. either whole molecules or groups of atoms rotating about molecular bonds.

System and method for monitoring changes in state of matter with terahertz radiation

An industrially hardened terahertz electromagnetic transmitter and receiver module ( ) is disclosed. The electromagnetic wave module has an optic ( ) which relays an optical pulse from the delivery fiber ( ) to the terahertz device. The relay optic ( ) allows for a greatly reduced optical spot size as compared to the output of the optical fiber. Thus, the sensitivity of the overall system is enhanced by improving the efficiency of the terahertz device. The relay optic ( ) allows the small spot of light to be aligned to the electromagnetic transmitter or receiver with sub-micron precision.

Compact fiber pigtailed terahertz modules

A semiconductor p-i-n photodiode having a substrate, an n layer coupled to the surface of said substrate, an i layer coupled to the surface of said n layer, and a carbon doped p layer coupled to the surface of said i layer.

Highly-doped P-type contact for high-speed, front-side illuminated photodiode

A photoresponsive pulser/sampler system for investigating electrical signals and responses in VLSI systems employs a microtip which communicates electrically and mechanically with the device under test, and electrically with an electrode via a photoresponsive gate. The photoresponsive gate is formed of interdigitated electrodes which have interdigital spacings therebetween on the order of 1 .mu.m. The structure of the invention is operable in the dual modalities of probe and pulser which share a common probe tip. Simultaneous implementation of the pulser and sampler functions is achieved with the use of a lock-in amplifier and the technique of difference frequency mixing, where the pulser optical pulse frequency is f.sub.1 and the gate optical pulse frequency is f.sub.2. Multiple photoresponsive gates coupled to a common probe tip and having respective electrodes are disclosed for achieving respective pulsing and sampling functions, and also for effecting S-parameter measurements. The lock-in amplifier is tuned to the difference between the two frequencies (f.sub.2 -f.sub.1). Piezoelectric apparatus is employed for translating the probe tip over the device under test.

High-speed, high-impedance external photoconductive-type sampling

A system for time-resolving ultra-short electrical waveforms of up to a few hundred gigahertz bandwidth is presented. The system utilizes a fast electro-optic modulator capable of subpicosecond responsivity. A CW (continuous wave) laser is used to probe the change in birefringence resulting in the modulator due to an induced electric field. The rapid change in the transmitted optical signal due to an equally rapid changing electric field (picosecond pulse) is then detected and temporally dispersed using a picosecond resolution streak camera. The modulator operates in a region close to minimum transmission where the average optical power is below the damage threshold for the photocathode of the streak camera and where small electrical signals can significantly modulate the transmitted beam. The system can be used in either sampling mode where the modulation and subsequent detection are repeated and the data accumulated at repetition rates as high as 100 MHz or in single shot mode.

Electro-electron oscilloscope

Electro-optic probes which are adapted to be placed in the fringe field from electrical signals propagating on conductors (which may be conductors of an integrated circuit) and which modulate optical pulses passing therethrough, for example by modulating the polarization of the light in accordance with the Pockels effect, utilize thin bodies of electro-optic material, such as a single crystal of GaAs in a manner to reduce physical damage to the probe and to the circuit and to precisely locate the probe in the field of the signal being measured, such as adjacent to the conductor of interest. The electro-optic material that is used may also be implanted with high energy ions of low Z materials (e.g. hydrogen or oxygen) so as to create charge trapping sites and to reduce the photo conductivity of the semiconductive electro-optic material sufficiently that the dielectric relaxation time (where photo current through the material reduces by ) is less than the duration of the optical pulses without eliminating the electro-optic (e.g. Pockels) effect. Charge carriers are trapped and cannot screen the electric field lines due to the electrical signal being measured which extend between the charge trapping sites where sufficient undamaged electro-optic material remains and enables the field and therefore the signal corresponding thereto to be measured.

Growing community of inventors

Ann Arbor, MI, United States of America

Steven L Williamson