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ABSTRACT Transparent conductors with high conductivity, optical transparency, and thermal stability are critical for next‐generation optoelectronic devices, yet such materials are scarce. Here, we demonstrate that epitaxial Cr₂AlC(0001)/Al₂O₃(0001) layers exhibit a unique combination of these properties. The optical transmittance of ultrathin layers reaches 85% at 900 nm and remains above 21% across the near‐infrared (NIR)ultraviolet (UV) range, in good agreement with first‐principles optical properties predictions which reveal a small plasma frequency and a low cross‐section for interband transitions. Cr₂AlC has a room‐temperature bulk resistivityρ_o= 42.5 µΩcm and an exceptionally small resistivity scaling with a negligible (<4%) resistivity increase down to 10 nm, an effective bulk electron mean free pathλ< 2 nm at both 295 and 77 K, and a temperature‐independent effectiveρ_oλ< 3 × 10⁻¹⁶Ωm²that is smaller than that of all known elemental metals. An 11.1‐nm‐thick Cr₂AlC layer achieves a benchmarkΦ_TC≈ 0.004 Ω⁻¹in the near infrared (900 nm), comparable to state‐of‐art transparent conductors including ultra‐thin silver and carbon‐based materials. These results, in combination with the known oxidation stability to 1073–1373 K, establish Cr₂AlC as a uniquely robust, high‐temperature stable and scalable transparent conductor, paving the way for advanced extreme‐environment optoelectronics and photonics. 

We present a new method for PM-fiber to photonic chip connection via laser fusion. This enables low cost and robust coupling with -1.1dB loss per facet while maintaining 20dB or greater polarization extinction ratio. 

Bragg-grating based cavities and coupler designs present opportunities for flexible allocation of bandwidth and spectrum in silicon photonic devices. Integrated silicon photonic devices are moving toward mainstream, mass adoption, leading to the need for compact Bragg grating based designs. In this work we present a design and experimental validation of a cascaded contra-directional Bragg-grating coupler with a measured main lobe to side-lobe contrast of 12.93 dB. This level of performance is achieved in a more compact size as compared to conventional apodized gratings, and a similar design philosophy can be used to improve side-lobe reduction in grating-based mirror design for on-chip lasers and other cavity-based designs as well.