Reception of Dual-Spatial-Mode CO-OFDM Signal Over a Two-Mode Fiber

We demonstrate the use of mechanical grating based mode converters to achieve two forms of dual-spatial-mode transmission: LP₀₁ and LP₁₁, and dual LP₀₁ modes. High modal extinction ratio (>; 20 dB) is shown for the mode converter within a 10-nm wavelength range. We first present 107-Gb/s coherent optical OFDM (CO-OFDM) transmission over a 4.5-km two-mode fiber using LP₀₁ and LP₁₁ modes where the mode separation is performed optically. We then show 58.8-Gb/s CO-OFDM transmission using dual LP₁₁ modes where the mode separation is achieved via 4 × 4 electronic MIMO processing.