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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Nano Optics

Diamond Nanophotonics

 

Staff members:  Bernd Sontheimer, Nikola Sadzak, Niko Nikolay

 

Fundings through:

 

salsa

 

 

School of Analytical Sciences Adlershof (SALSA)

einstein

 

 

Einstein Foundation


 

1. Nanodiamond-based multi-functional probes combining nitrogen-vacancy center magnetometry and plasmonics

 

Understanding the mechanisms of chemical and biological processes at the nanoscale has been a major challenge of several research fields, where different approaches have been exploited in order to develop sensing tools capable of being implemented in complex environments [1]. Here, the requirements that a measurement system should satisfy are multiple: nanometer spatial resolution, high specificity of the sensor for the target object, high signal-to-noise ratios and stability in dynamic environments where a manifold of interactions between chemical species are occurring.

Nowadays, different method are being tested for such purposes: AFM/STM with functionalized probes, surface or tip enhanced Raman scattering, functionalized plasmonic nanoparticles, etc.

In this project, we implement a bottom-up approach that consists in combining different nanostructures and nanoparticles in order to achieve a multilateral sensing capability on our target systems. The core of such a multi-functional nanoprobe is represented by a magnetic field sensor realized through through the deterministic control of a single nitrogen-vacancy defect center in nanodiamond. This is a stable, bright quantum light source whose electron spin can be manipulated via microwave pulses while the outcoming state can be readout via fluorescence intensity measurement [2]. By allowing the NV center electron spin to interact with other electron/nuclear spins in a controlled way, a nanoscale magnetometer can be realized, having a nanometer spatial resolution [3]. Furthermore, by using AFM manipulation of nanodiamonds embedding NV centers, a deterministic positioning of the sensor can be obtained [4], while scanning probe approaches are either possible. By combining single NVs in nanodiamond with plasmonic and magnetic nanoparticles [5], performance enhancement on magnetic field measurements is being researched, while plasmonic nanostructure allow the probe to be used in Raman scattering measurements on chemical species surrounding the nanoprobe. Our study is meant to pave the way toward a biologically-compatible multi-functional sensor which gives access to local, nanoscale NMR/EPR information, as well as Raman active vibrational modes of the target system.

 

Fig1.1 Fig1.2

Left: sketch of a nanodiamond containing a paramagnetic nitrogen vacancy center (J. Wolters, N. Sadzak). Right:: on-chip AFM manipulation of nanoparticles allow to study distance dependent mutual interactions.

 

[1] Jarzyna, Peter A., et al. "Multi-functional imaging nanoprobes." Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology 2.2 (2010): 138-150.

[2] Aharonovich, Igor, et al. "Diamond-based single-photon emitters." Reports on progress in Physics 74.7 (2011): 076501.

[3] Taylor, J. M., et al. "High-sensitivity diamond magnetometer with nanoscale resolution." Nature Physics 4.10 (2008): 810-816.

[4] Schell, Andreas W., et al. "A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices." Review of Scientific Instruments 82.7 (2011): 073709.

[5] Schietinger, Stefan, et al. "Plasmon-enhanced upconversion in single NaYF4: Yb3+/Er3+ codoped nanocrystals." Nano letters 10.1 (2009): 134-138.

 

Contact:   

Nikola Sadzak

 

2. ActiPlAnt

 

Experiments with single quantum dots, as well as nitrogen vacancy centers often suffer from low detection and absorption efficiencies. Therefore, this project focuses on controlling these properties, e.g: emitter lifetime shortening, directionality of emission and enhancement of emission/absorption.

Recent experiments revealed plasmonic nano-antennas as suitable candidates for the manipulation of the just mentioned properties and therefore they are candidates of choice within this project.

The first idea of an integrated device, which might provide a great field enhancement [1], as well as a directional emission [2] is shown in figure 2.

The full process: theoretical design and optimization, sample fabrication, assembly with nanoemitters and the optical characterization are done by the collaborators of this project. The expertise of Nanooptics group within this design cycle are the assembly by pick and place [3] (see figure 2) and the optical characterization of the final devices.

 

Fig2.1 Fig2.2
Fig. 1: Pick and place process with an AFM, assisted by a confocal microscope, taken from [3]. Fig. 2: Combination of a bullseye-antenna with a plasmonic needle, taken from [1].

 

[1] Normatov, A., et al. “Efficient coupling and field enhancement for the nano-scale: plasmonic needle”, Optics express 18, 14079-14086 (2010).

[2] Harats, M. G., et al. “Full Spectral and Angular Characterization of Highly  Directional  Emission from Nanocrystal Quantum Dots  Positioned on Circular Plasmonic Lenses.”, Nano Lett. 14, 5766-5771 (2014).

[3] Schell, A. W., et al. “A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices.”, Review of Scientific Instruments, 82(7), 073709 (2011).

 

Contact:   

Niko Nikolay

 

3. 3D quantum photonic devices based on single emitters in laser-written microstructures

 

To fully integrate quantum optical technology, active quantum systems must be combined with microstructures and optical interconnects that are capable of routing photons in three diemsnsions (3D) on a chip. Recently our collaboratores at KIT have been able to facbricate such structures for the first time by using two-photon laser lithography and a photoresist containing nanodiamonds hosting nitrogen vacancy-centers.[1]  This one-step fabrication technique is easy to implement, scalable and enables almost arbitrary 3D quantum optical structures.

At our group we design and characterize such structures and pursue different approaches for efficient light collection and photon routing. Combining such structures with microwave antennas can be a first step towards an integrated single spin magnetometer.

 

(a): Sketch of the direct laser writing process. A femtosecond laser beam is focussed into the photoresist in order to polymerize well defined 3D structures. (b): Scanning electron micrograph of such a structure after development containing several key photonic elements, such as waveguides, couplers and microdisc resonators. Scale bar is 5 μm. [1]

 

1] Schell, A. W.,et al. “Three-dimensional quantum photonic elements based on single nitrogen vacancy-centres in laser-written microstructures.”, Scientific Reports 3, Article number: 1577; doi:10.1038/srep01577 (2013).

 

[2] Schell, A. W.,et al. “Laser-written parabolic micro-antennas for efficient photon collection.” Appl. Phys. Lett. 105, 231117  doi:10.1063/1.4903804 (2014).

 

Contact:   

Bernd Sontheimer