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Barak Raman system

MicroRaman system with excellent performance, total flexibility

Laser Focus World has highlighted a recent paper showing how multi-frequency NSOM maps optical forces without a photodetector.  This groundbreaking research was conducted by researchers at University of Central Florida and CNRS in Paris with a Nanonics Multiview system and was able to map optical forces using a tuning fork architecture without a photodetector.  This paper was published in Nanotechnology, 2014 (vol 25, p. 035203) and was highlighted in our January newsletter.

 

MICROSCOPY: Multi-frequency NSOM maps optical forces without a photodetector

03/03/2014

By Gail Overton
Senior Editor

 

Near-field scanning optical microscopy (NSOM) uses a sharp probe tip or a small aperture to scatter the electromagnetic field near the surface of a sample to gather high-spatial-resolution information present in the surrounding evanescent field. The subwavelength field information is then converted to a propagating far-field and measured with a photodetector to image the sample.

In a new technique called multifrequency NSOM, researchers at the College of Optics and Photonics (CREOL) at the University of Central Florida (UCF; Orlando, FL) and CNRS Institute Langevin (Paris, France) apply both an electrical signal and an optical signal to the tuning-fork architecture to map both surface topography and the spatial distribution of optically induced forces acting on the probe.1 Because the method does not require a photodetector for radiation-distribution mapping, broadband detection of light is possible using a single probe.

Optically induced force measurement
In the experimental setup, an oscillating quartz tuning fork with a sharp probe tip (a conventional gold-coated, pulled-fiber 100-nm-diameter aperture) affixed to one arm is piezoelectrically driven just above the sample surface and the probe position is maintained through a feedback mechanism for the first resonance signal to enable surface topography mapping as in standard atomic force microscopy (AFM). When a second oscillation is applied to the probe tip on one arm of the tuning fork, an additional higher-order resonance can be monitored that yields information on the forces acting upon the tip.

The probe is situated above the sample surface and is illuminated by 635 nm laser light coupled out of a single-mode fiber and maintained at an intensity of 0.36 mW/μm2. While the electrical signal enables topography mapping, the amplitude and phase of the optically induced resonance signal depend directly on the optical force acting on the tip.

 

Oscillating a scanning near-field optical probe at two different frequencies—one driven electrically to provide positional feedback and the other one by modulating the electromagnetic fields acting on it—allows simultaneous mapping of the topography (a) and optical forces (b) across the surface of a gold nanosphere lithography sample. (Courtesy of CREOL)

Using standard coupled equations of motion for the damped, driven NSOM harmonic oscillator that include both the electrical and optical frequency parameters, the amplitude and phase of the optical signal can be obtained. From variations in these two values, the magnitude of the optical force acting on the probe and its gradient can be extracted, yielding information on optical forces occurring spatially within the sample under test.

In an experiment, the force distribution was measured across a gold nanosphere lithography sample consisting of 0.453-μm-diameter gold spheres placed against a glass substrate and separated with 260 nm center-to-center spacing. Using both a tuning fork and a cantilevered-probe NSOM, near-field optical forces were measured with better than wavelength/50 resolution.

In the context of NSOM practice, CREOL professor of optics Aristide Dogariu says, “This multifrequency approach permits measuring—simultaneously—multiple aspects of the near field in the proximity of a sample and it also provides means to decouple the effects of different forces acting on the probe. Most importantly, it allows to separate the possible influence of thermal effects induced by the electromagnetic radiation. Without sacrificing spatial resolution, this technique not only circumvents the need for photon detectors but it also complements traditional approaches for optical characterization of metamaterials, plasmonic nanostructures, and biological structures.”

REFERENCE
1. D. C. Kohlgraf-Owens et al., Nanotechnol., 25, 035203 (2014).

 

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February 2014 Newsletter

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February 2014 - In This Issue:
Research Focus: Scanning Thermal Microscopy
Specialized thermal probes
User News: SThM measures nanoscale heating around photonic devices
Nanonics at APS in Denver!
Meet Nanonics staff member Dr. Hesham Taha
 

Scanning Thermal Microscopy (SThM)

 

Scanning Thermal Microscopy (SThM) is a mode of atomic force microscopy where the local temperature and thermal conductivity are mapped simultaneously with topography.   Among its important applications are detection of phase changes, calorimetry, and discriminating materials.

 

SThM maps phenomena such as thermal expansion and thermal conductivity on the nanoscale, which can provide information on the chemical structure and can be a useful supplement for other measurements such as NSOM and near field Raman.

 

In this method, the probe is sensitive to local temperatures, with a common design - employed by Nanonics  - being a thermocouple probe where its  temperature is monitored by a thermocouple junction at the tip.  These probes thus provide combined topography and high resolution thermal images.  Especially when combined with the Nanonics multiprobe SPM design, nanoscale thermal characterization is possible using one probe to induce heating while the second probe monitors the heat propagation.

 

Nanonics has been a pioneer in the design and manufacture of specialized probes (see below) for these measurements for optimal experimental results. 

 

See examples of applications of scanning thermal microscopy on our website including our results on  thermal resistance  and conductivity imaging of a chip and of GaN nanowires.

 

Nanonics offers specialized probes for thermal measurements

 

Using over a decade's experience in manufacturing nanoprobes for a wide variety of sophisticated measurements, Nanonics manufactures thermocouple probes and dual-wire thermoresistive probes for thermal measurements.

 

The thermocouple probes (see schematic to right) consist of a tapered wire running through a metal-coated, glass nanopipette. The external metal coating extends over the protruding wire to create a junction across which the voltage drop is temperature dependent, with an incredibly fast time response enabling both static and dynamic thermal measurements in localized regions with high precision. Nanonics also provides thermoresistive probes that provide intermittent contact imaging of surfaces. 

 

All Nanonics probes feature a highly exposed tip for optical sensing with free optical access from above and below and are suitable for operation with all Nanonics systems including Multiprobe operation. Click here for more information on Nanonics probes.

 

USER NEWS - Scanning Thermal Microscopy measures nanoscale heating in photonic devices

  

As the miniaturization of photonic devices continues to drive down their dimensions and increase the data rates, heating and heat removal in these devices pose significant limitations to their further improvement and development.  Methods that can probe thermal conductivity and dissipation on the nanoscale are thus critical to future development and design of thermally stable devices that can be densely integrated on a chip.  The comparison of NSOM and thermal measurements enable characterization and comparison of the thermal distribution and optical profile.

 

Using a Nanonics Multiview 4000 Multiprobe system with Nanonics thermal probes, researchers Uriel Levy et al. (Optics Express, 2013, vol. 21, no. 24, p.  29195) have successfully measured  a temperature rise in a photonic device known as a silicon micro ring resonator (MRR) of approximately 10 degrees for power levels of 2mW in the waveguide. The authors hypothesize the self-heating is caused by free carrier absorption in the doped silicon.   This study shows that the role of MRR as building blocks in thermally stable Si photonic devices could be problematic unless future designs address this heating issue.

Thermal images of the doped Si MRR (a) in-resonance (b) out of resonance and (c) with laser turned off
Nanonics at APS
Visit us in Denver!  Nanonics scientists will be in booth 1008 and giving technical talks:
 

Thursday, March 6, 2014

Abstract: T24.00002    11:51-12:03 Room 504
"Multiprobe Electrical Measurements of Carbon Nanotubes with On-line Raman Scattering"
 
Abstract T24.00013     2:15-2:30  Room 504
"PiezoForce and Contact Resonance Microscopy Correlated with Raman Spectroscopy applied to a Non-linear Optical Material and to a Lithium Battery Material"
Meet Nanonics staff!
This month we profile Dr. Hesham Taha.
Current position at Nanonics: 

Hesham is Manager of Support and After Sales Services.

He has led a variety of R&D projects and performed dozens of installations globally of a variety of Nanonics systems.  Hesham enjoys interacting with customers and works closely with them on their experiments so they get the best use of their instruments.

Academic Background:  

Hesham holds a Ph.D in Applied Physics from the Hebrew University of Jerusalem in the field of SPM nanolithography.

Family:  Hesham is married to Sahar and they have a son.
Hobbies:  Fishing and horseback riding 

Where are you presenting your research?
Please let us know where you are presenting your research and we will be happy to share the news!
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January 2014 Newsletter

 
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January 2014 - In This Issue:
Research Focus: Tuning fork probes and feedback
User news: Detection of near-field optical forces
Nanonics at Photonics West
Meet our staff member Rimma Dechter
Tuning fork probe

Tuning fork feedback mechanism for ultimate force sensitivity

 

Tuning forks offer significant advantages and increased sensitivity over conventional Si probes in large part due to their high quality factors (Q of 10x and higher.)   Tuning forks in force spectroscopy have especially begun to show exciting results that push the measurement's possibilities.  Over the last decade, Nanonics has developed instruments using a NanoToolKit of such probes that are increasingly being used with on-line force spectroscopy.  A demonstration of the force sensitivity of these probes is the measurement of 1.6 pN for the force of a single photon. [D. C. Kohlgraf-Owens et al "Mapping the mechanical action of light," Phys. Rev. A 84, 011807R (2011)]

 

Besides force sensitivity, tuning forks offer other advantages over optical beam deflection and conventional Si probes.  Tuning forks have much stiffer (spring constant of ~2600 N/m and greater) than standard silicon cantilevers.  As a result, the problem of "jump to contact" instability that limits the optical beam deflection based feedback methods is eliminated, and this permits the study of forces in the proximal 10-20 nm above a surface.  Smooth approach curves together with lack of adhesion ringing upon withdrawal is combined with additional advantages of no feedback laser interference; these features are important for semiconductor electrical probing and combinations of AFM with Raman spectroscopy that Nanonics has pioneered.  Furthermore, tuning forks in force spectroscopy enable the point of contact with the surface to be accurately measured for the first time.  For all these reasons and its ease of use, tuning forks are becoming an ideal choice for new horizons in experiments requiring the ultimate tip-sample control stability and force sensitivity from areas of bioimaging, to physics of devices, and to single molecule and polymer spectroscopy.

 
Topography color coded with ampl. measured at optical driving frequency
USER NEWS - Detection of near-field optical forces
 

The power and sensitivity of tuning fork feedback was demonstrated in a recent groundbreaking publication in high resolution apertureless imaging by Prof. Aristide Dogariu's group at University of Central Florida.  Using a Nanonics Multiview 4000 system, his team mapped near-field optically induced forces with sub wavelength spatial resolution (Kohlgraf-Owens et al., Nanotechnology, 25, 034203 [2014]). The scientists describe a new method, multifrequency NSOM, performed with tuning forks/tuning fork feedback and cantilever probes/optical beam deflection feedback.   By exciting the probe's oscillation at two difference frequencies, they measured the amplitude and phase  at the optical modulation frequency on a gold nanosphere sample (see image on right) revealing  an amplitude that was lowest over the gold pads, moderate over the glass, and highest near the edges.  The method opens a new horizon of apertureless imaging of optical fields with very high spatial resolution over a large range of wavelengths - including far-IR and THz - and it can be accomplished without using photodetectors, a regime that to-date lacks a competitive alternative for detection!  Professor Aristide comments "We are excited about the potential of multi-frequency NSOM for using photonic forces for apertureless imaging of optical fields in a wide variety of wavelength regimes from the visible to the IR."

Nanonics at Photonics West
 
Nanonics founder and CEO Aaron Lewis, a pioneer in near-field optics, will be at Photonics West. Please email us at info@nanonics.co.il to schedule a discussion and time to meet with him.
 
Professor Lewis is presenting on a variety of topics in February in San Francisco:

1) Sunday, 5:50pm, BIOS 8939-11 (ORAL) "Understanding the TERS effect with an on-line tunneling and force feedback using multiprobe AFM/NSOM with Raman integration
2) Monday, 2:50pm, OPTO 8992-24 (ORAL) "Combined far-field and multiprobe near-field imaging of hybrid photonic devices"
3) Monday, 4:20pm, OPTO 9006-16 (ORAL) "Addressing the inverse problem of imaging:  A noniterative exact solution fo rphae in imaging based on microHolography"
4) Wednesday, 6:00pm, OPTO 8988-64 (POSTER) "Piezoforce and contact resonance microscopy correlated with Raman spectroscopy applied to a non-linear optical material and to a lithium battery material"
5) Thursday, 11:30am, OPT 8999-39 (ORAL) "Ultrasensitive force detection of photonic phenomena with tunin fork based frequency modulation"
Meet Nanonics staff!
Welcome to our newest segment in our newsletter where we will be profiling a member of our staff.  We start this month with Dr. Rimma Dechter, a name that is familiar to many Nanonics customers.

Current position at Nanonics:  Manager of Analytical Services. In this role Rimma heads the department that makes measurements on customer samples in the wide variety of characterization needs Nanonics offers from conventional scanning probe microsopy to near field and Raman measurements to multiple probe experiments.
Academic Background:  PhD in Applied Physics from Hebrew University
Family:  married + 3 kids
Hobbies:  genealogy
What I like about working at Nanonics:  The aspect I enjoy the most is the tremendous amount of innovation that goes on in our company to meet customers needs. It is exciting to interact with customers and learn about their instrumentation requirements for their research; I then work with my colleagues to develop new, out of the box solutions to meet their needs.
 
Where are you presenting your research?
Please let us know where you are presenting your research and we will be happy to share the news!
For more information, please contact us at info@nanonics.co.il or call us at +972-2-678-9573, (US toll free 1-800-289-7162)

 way to increase sensitivity in TERS experiments from complicated biological samples by providing another platform for preparing complex biological molecules that can be probed by the ultrasensitive TERS method.

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Microscopy Today for Hydra AFM 2010

 

 

Microscopy Today 2010

The Nanonics Hydra biological SPM was selected as one of the top 10 innovations by Microscopy Today. Read more about the Hydra.

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R&D 100 for Multiview 4000 in 2007

 

R&D 100 award 2007 

R&D 100 2007

The Multiview 4000 was selected as one of the top 100 technologically significant new products in 2007 for its breakthrough multiple probe technology. See more details on the Multiview 4000.

 

 

Microscopy Today Award 2013

Presented to Nanonics for development of a novel integrated tool for the ultimate 3D characterization: the 3TB 4000. Read more about it on our website and in the November 2013 Microscopy Today (Volume 21) journal.

 

 

R and D Award 1993

Presented to Nanoptics, For the development of Glass capillary X-ray concentrator 

Selected by R&D magazine as one of the 100 Most Technologically Significant new Products of the year 

 

 

The Laser Focus World Commercial Technology Achievement Award 1996

 
 

Presented to Nanonics Ltd. Jerusalem, Israel for 3-D scanner for the optical/scanned probe microscopist.

The Laser Focus World Commercial Technology Achievement Awards recognize significant and lasting achievements in commercial electro-optical technology.

 

 

 

 

 

 The Photonics Circle of Excellence Award 1996

 

Nanonics Imaging Ltd. has been cited by Photonics Spectra Magazine for developing one of the twenty-five best new products of the year.

This award is bestowed on Nanonics for the NSOM/SPM-100 Confocal™ (now called the MultiView 1000™) in recognition of excellence, innovation and achievement in the field of photonics technology.

 

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