AiDi Corp. has developed a Fourier-transform, integrated-optic spatial heterodyne (FISH) spectrometer with an ability to correct interferometer defects using electrical data postprocessing at the highest level of resolution available — less than 10 GHz. The FISH spectrometer utilizes an interferometric Fourier transform technique called spatial heterodyne spectroscopy (SHS) to measure optical spectra with high optical throughput. AiDi, a privately held optical communications company with offices in Japan, China and the US, has developed a proprietary optical waveguide SHS method employing an interleaved Mach-Zehnder interferometer array that enables a highly compact FISH (see image below). AiDi Corp. has developed an optical waveguide spatial heterodyne spectroscopy technique employing an interleaved Mach-Zehnder interferometer (MZI) array that enables a compact Fourier-transform, integrated-optic spatial heterodyne spectrometry. (Illustrations: AiDi Corp.) The practical importance of the AiDi Fourier-transform spectrometer is the ability to correct for interferometer defects (fabrication errors) in an electrical data-processing stage. The FISH method can then achieve sub-10-GHz resolution, which is almost impossible with several centimeter-size bulk-optic spectrometers. The image below shows original and measured signal spectra of a FISH device with 20-GHz resolution. The spectral range of the FISH device can be made arbitrarily narrow or wide depending on the application. For visible color measurement, it can be designed to cover a 340- to 780-nm spectral region with 5-nm resolution. Signal spectrum measured with FISH with 20-GHz resolution. For near-infrared applications such as water vapor characterization, the FISH device can measure absorption spectra with 0.05 nm (~10 GHz) resolution in the 1365-nm region. Water vapor is the most important greenhouse gas, contributing more than 80 percent to the total greenhouse effect. Water vapor not only plays a central role in weather and climate phenomena but in atmospheric chemical processes as well. It is very crucial to determine the details of the various processes that move air across the tropical tropopause into the stratosphere and the relative importance of these processes in determining stratospheric humidity. "We are planning to develop this technology for both environmental and biotechnology applications, especially the study of global warming and early diagnosis of different types of diseases," said Kenzo Ishida, president and CEO of AiDi. AiDi is scheduled to present the new spectrometer at the 15th European Conference on Integrated Optics (ECIO) in Cambridge, England, April 7-9, 2010. For more information, visit: www.aidicorp.com