Spectrometers – On-Chip Open Channels Design

In the past ten years, there has been a lot of research into on-chip spectrometers with customized spectral ranges and small sizes. When splitting various frequencies, there is a trade-off between resolution and size because the propagation length usually scales inversely with the frequency resolution.

On-chip compressive spectrometers can be used with scattering media in the diffusive domain because they offer a long light path and multipath interference in a small space.

However, poor light transmission through the diffusive medium affects the performance. It has been discovered that “open pathways” allow light with specific wavefronts to transmit highly through the medium. Researchers demonstrate that a scattering structure can be designed so that open channels match target I/O channels to optimize transmission while maintaining the dispersive properties typical of diffusive media. To be more precise, they create a scattering structure using inverse design so that the open channels fit the output waveguides at the required wavelengths.

Researchers suggested a 110 multiplexer with a footprint of just 9.4 m by 14.4 m, spanning a band of 500 nm in the mid-infrared spectrum. The structures are also extremely suitable for manufacturing because of their straightforward geometry, which consists of circular holes etched with diameters ranging from 200 to 700 nm in a dielectric slab. The suggested technique is crucial in pursuing integrated lab-on-a-chip spectroscopy with compressive sensing.

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