The paper by Shalaev et al. reports the experimental observation of a negative refractive index ($n' \approx -0.3$) in an array of pairs of parallel gold nanorods at the optical communication wavelength of 1.5 μm. This effect is attributed to plasmon resonance in the nanorod pairs for both the electric and magnetic components of light. The refractive index is determined from phase and amplitude measurements of transmission and reflection, which are in good agreement with finite difference time domain (FDTD) simulations. The phase of the transmitted wave is critical for identifying the negative refractive index, emphasizing the importance of phase measurements. The study demonstrates the feasibility of achieving negative refraction in the optical range, opening new avenues for designing metamaterials with unique optical properties. The results are supported by theoretical predictions and simulations, showing excellent agreement between experimental data and FDTD simulations. The negative refractive index is observed in a spectral range between 1.1 μm and 1.6 μm, with a magnitude of $n' \approx -0.3$ at 1.5 μm. The work highlights the potential for further optimization to reduce losses and enhance the magnitude of negative refraction, leading to new applications in optics.The paper by Shalaev et al. reports the experimental observation of a negative refractive index ($n' \approx -0.3$) in an array of pairs of parallel gold nanorods at the optical communication wavelength of 1.5 μm. This effect is attributed to plasmon resonance in the nanorod pairs for both the electric and magnetic components of light. The refractive index is determined from phase and amplitude measurements of transmission and reflection, which are in good agreement with finite difference time domain (FDTD) simulations. The phase of the transmitted wave is critical for identifying the negative refractive index, emphasizing the importance of phase measurements. The study demonstrates the feasibility of achieving negative refraction in the optical range, opening new avenues for designing metamaterials with unique optical properties. The results are supported by theoretical predictions and simulations, showing excellent agreement between experimental data and FDTD simulations. The negative refractive index is observed in a spectral range between 1.1 μm and 1.6 μm, with a magnitude of $n' \approx -0.3$ at 1.5 μm. The work highlights the potential for further optimization to reduce losses and enhance the magnitude of negative refraction, leading to new applications in optics.