Compact, astigmatism corrected cross-grating spectrometer

Compact cross-grating spectrometers are inspired by classical high-end Echelle spectrometers and allow to acquire a large spectrum with a high spectral resolution in a single shot. To decrease the size of an Echelle spectrometer substantially, a cross grating was employed combining both required dispersive functionalities. First, an Echelle grating diffracts light in several higher diffraction orders, while a superposed, perpendicularly oriented cross-disperser is used in first diffraction order. In this contribution, we report on the realization of a cross-grating spectrometer employing a folded reflective beam path. A toric-convex mirror was introduced allowing aberration compensation. We present the basic concept and optical design of the system and discuss the mechanical implementation and the adjustment process. Here, different laser sources and gas emission lamps are used to realize the system and derive the optical performance. In particular, the spectral resolution in the different diffraction orders is determined for the realized device.

Compact and Low Crosstalk Echelle Grating Demultiplexer on Silicon-On-Insulator Technology

We report on the design of an ultra-compact integrated wavelength demultiplexer in echelle configuration for the optical O-band realized on silicon-on-insulator technology. The device has four channels with channel spacing of 800 GHz and a small footprint of 260 × 83 μm2. Channel crosstalk lower than −28 dB across the four channels is experimentally demonstrated along with insertion losses of −1.5 dB.