Differential 8-APSK monolithically integrated dual-EML transmitter for flexible coherent PONs

Abstract

We experimentally demonstrate a simultaneous amplitude and phase modulation of a monolithically integrated dual electro-absorption modulated laser. The proposed technique combines a 4-ary direct phase modulation with a two-level amplitude modulation obtaining an 8-ary amplitude phase shift keying external-modulator-free transmitter (Tx). Its performance was tested up to 7.5 Gb/s in a 25 km single-mode fiber link with intradyne coherent detection. A receiver sensitivity of -42.5¿¿dBm was achieved at a forward error correction limit bit error ratio =4×10-3. The results show that the proposed system can be an efficient flexible Tx for next-generation passive optical networks.