Experimental Verification of Transmittance and Harmonics in External Optical Intensity Modulation

Modern communication systems, such as 5G and future 6G require enormous bandwidths from the interconnecting fronthaul and backhaul networks. Extremely high data rates are required in long-haul fiber optic communication systems, as well as in cloud-core networks and data centers. Optical modulators and ultra-fast photodetectors with modulation bandwidths beyond 100 GHz are commercially available since several years. When integrating these building blocks together into entire systems, a good understanding of spurious and unwanted signals, such as modulation harmonics is required. This paper gives experimental verification for the modulation harmonics generated in interferometric type electro-optical modulators having microwave modulation bandwidth. A good agreement is shown with the theoretical investigations.