Photonics

Photonics, the study and characterization of light and its transmission, eccompasses an expansive scope of research and applications. Light sources, lasers, transmission and modulation continue to be investigated. Industries as varied as telecommunications, health, and manufacturing all employ photonic research.

The Nanonics Multiview SPM systems offer the ideal solution for the versatility that is necessary for a multi-dimensional approach to photonics, integrating AFM, NSOM, and SEM in one flexible platform.

This study demonstrates a simple method for phase mapping characterization of nano photonic structures.

By exploiting the intrinsic oscillations of an apertured NSOM probe, phase mapping is readily achieved.  The system can be integrated to an existing NSOM setup in relative ease and has high potential as a characterization tool of various nanophotonic structures. The maps provide significant information about the phase and amplitude of the electromagnetic field within the waveguide.

The measurements in this study were obtained with the Nanonics MultiView4000 integrated with a fiber interferometric setup.   Light is emitted from a laser into a beam splitter sending the majority of light into the silicon waveguide. The NSOM probe was brought into proximity with the waveguide and kept in contact with its surface with intermittent contact. The light was collected by the NSOM tip, combined with the reference beam using a beam splitter and detected by a Photo Detector.

The open architecture of the MultiView 4000 combined with the ability to scan the tip are critical elements to the setup. The ability to keep the sample stationary to the input light while scanning the tip over the structure is a key feature. In this manner the electromagnetic field inside the waveguide is unaffected during the measurement. 

Reference: Near field phase mapping exploiting intrinsic oscillations of aperture NSOM probe

Stern, Liron, Boris Desiatov, Ilya Goykhman, Gilad M. Lerman, and Uriel Levy

Optics express 19, no. 13 (2011): 12014-12020.

Seen above multi-dimensional characterization of the distribution of light from a quantum wire laser.

The collection mode image was collected by the near-field optical fiber and passed through a monochromator or spectrograph to a detector. 

The image was then made at  805 nm and 805.8 nm.  This small wavelength change caused a large change in the distribution of light. 

The far-field optical resolution in this case is approximately equal to the 0.5 micron bar on the image and such a pixel size would have completely missed the possibility to image this change in light distribution with wavelength from this nanophotonic active device.

(Right) Note the higher temperature in the top left corner of the zoomed out thermal image.

The light distribution and the thermal imaging shows that the thermal characteristics are related to the p injection current rather than the light intensity.

Multiprobe systems are ideal for such thermal and optical characterization.

The images below detail the dramatic effects on cavity structure of a DFB laser, in response to varying the injection current levels.

These changes can be observed in 3 dimensions: the topography of the cavity, the NSOM light distribution, and in a collage of the AFM - NSOM light distribution.

The images demonstrate the correlation between current levels and laser cavity height.