A novel spectrometer concept is analyzed and experimentally verified. The method relies on probing the speckle displacement due to a change in the incident wavelength. A rough surface is illuminated at an oblique angle, and the peak position of the covariance between the speckle patterns observed in the far field with the two wavelengths reveals the wavelength change. A spectral resolution of 100 Mhz is argued to be achievable.
Silicon photonics is now considered the photonics platform of choice for short-reach data center single mode pluggable transceivers. With the emergence of co-packaged optics concepts, it can also enable high performance computing with power-efficient interconnect, but also Lidar system integration or even optical quantum computing. In this paper we will present an overview of what can be achieved in state-of-the-art silicon photonics platforms and we will discuss some of the emerging technology trends. In particular, we will discuss the integration of LPCVD SiN in an active silicon photonics platform.
Based on a previously devised speckle-based setup for probing minute wavelength changes for a coherent field [1], [2] we will here present the first experiments where these changes are resolved on a millisecond time scale. The setup is based on probing the lateral shift of a speckle pattern arising from a slanted rough object, the speckle displacement being linearly proportional to the wavenumber change. Thus, by shearing the speckle pattern across a grating-like structure [3],[4] and [5], a frequency proportional to the frequency of the wavelength change can be derived as will the irradiance. Thus, a cordial display of the complex field amplitude may be obtained with a high temporal resolution and a reasonable spectral resolution. The spatial filter is here preliminarily implemented by recording the speckle pattern with a CMOS array with subsequent digital image processing mimicking the use of a spatial filter.
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