Morphology Engineering Enabled Mid-Infrared Ultra-Dense Waveguide Array with Low Crosstalk
The mid-infrared (MlR) band holds signifcant promise in various felds.including thermal imaging, spectroscopy sensing, infrared countermeasuresand free-space communication, due to its distinctive characteristics. Despitesubstantial efforts that have been dedicated to building on-chip photonicintegrated circuits for MIR, enabling system miniaturization and broadeningapplication scopes, the challenge ofcrosstalk among closely packedwaveguides persists, hampering improvements in integration density anddevice performance. Here, a morphology engineering approach is proposed totailor coupling and suppress crosstalk within a densely arranged waveguidearray. These results demonstrate that by introducing a periodic Bezier curve toadorn the waveguide trajectory, coherent coupling can be disrupted, isolatingeach waveguide and minimizing crosstalk in the array. An experimentallydemonstrated eight-channel waveguide array with a half-wavelength pitchoperating at 3.55 μm exhibits crosstalk suppression exceeding -29 dB,representing an 8 dB improvement compared to a sinusoidal trajectory. Thismethodology, ofering precise control ofon-chip light guiding, coupling, androuting, provides a promising perspective for high-density design in photonicintegrated circuits at MIR.
