Kalyani Chaganti

A simple miniature optical spectrometer with a planar waveguide grating coupler in combination with a plano-convex lens

A miniature optical spectrometer with a thin-film planar waveguide grating coupler in combination with a miniature plano-convex focusing lens has been investigated. With optical part of the spectrometer as small as 0.2 cubic cm, the spectral resolution varies from 0.3 nm to 4.6 nm within the wavelength range 488.0 nm - 632.8 nm.

Concept of a miniature optical spectrometer using integrated optical and micro-optical components.

We describe the concept of a super compact diffractive imaging spectrometer, with optical components a few millimeters across in all dimensions, capable of detecting optical fluorescence spectra within the entire visible spectral range from 400 nm to 700 nm with resolution of the order of 2 nm. In addition, the proposed spectrometer is capable of working simultaneously with multiple, up to 35, independent input optical channels. A specially designed diffractive optical element integrated with a planar optical waveguide is the key component of the proposed device. In the preliminary experimental tests, a uniform waveguide grating with a microlens was used to mimic operation of the diffractive optical element. A microspectrometer with optical components measured below 1 cm in all dimensions covers the spectral range from 450 nm to 650 nm and shows a spectral resolution of 0.5 nm at wavelengths close to 514 nm and 633 nm.

Sub-micron grating fabrication on hafnium oxide thin-film waveguides with focused ion-beam milling

Uniform period sub-micron gratings have been fabricated using focused ion beam milling on hafnium oxide waveguides. Atomic force microscopy indicates that the gratings have smooth and uniform profiles. At the period of 330 nm, the largest peak-to-peak height that was achieved was 85 nm. Scattering at the grating imperfections was found to be at least two orders of magnitude weaker than the intensity of the diffracted order.

Building a diffractive imaging micro spectrometer

A diffractive imaging micro spectrometer that exhibits good spectral and spatial resolution is a very useful lab-on-a-chip device that can be integrated into biosensors. We have demonstrated the possibility of such a micro spectrometer experimentally.

Diffractive imaging micro-spectrometer

Optical multiplexers/demultiplexers developed for the telecommunication industry, at the level of the basic principles, perform essentially the same functions as general-use optical spectrometers. The spectrometer design inspired by the telecom devices would represent an extremely compact device compatible with the manufacturing procedures in integrated optoelectronics and micro-optics. In this paper we summarize our recent results on development of a miniature optical spectrometer. The spectrometer uses a diffractive optical element integrated with a planar optical waveguide. It is designed to provide spectral resolution of at least 2nm in the entire visible spectral range from 400nm- 700nm, and simultaneously resolve spectra from up to 35 independent optical inputs. The optical part of the spectrometer fits volume below 10mm3. The spectrometer is designed for on-chip diagnostic systems, in particular for fluorescence detection of hazardous materials. A device prototype with diffractive optical element fabricated using electron beam lithography is manufactured and tested.

Diffraction Gratings for a Compact Integrated Optical Micro-Spectrometer

The integrated optical micro-spectrometer based on of focusing diffraction grating fabricated by e-beam lithography with the size of optical part less than 0.1 cm and spectral resolution at least 5 nm has been developed.

Model-independent method for the determination of guiding thin-film optical parameters

A method for the determination of the optical constants of thin films based on the combination of a waveguide measurement procedure with the spectroscopic measurements made from the UV to the IR is presented. As a test material AlN thin film on sapphire substrates is investigated.

Miniature Optical Spectrometer with Sub-Nanometer Resolution

Combining integrated optics with free-space microoptics allows for a miniature spectrometer with optical components occupying less than 1cm3. Spectral resolution of 0.5nm over 450nm-650nm range is experimentally verified. The spectrometer is designed for on-chip systems.