Monolithically Integrated Directly Modulated ADR-DFB Laser Array in the O-Band

A four-channel directly modulated active distributed reflector DFB (ADR-DFB) laser array monolithically integrated with a 4 × 1 multimode interference coupler through vertical couplers has been demonstrated in the 1.3 μm wavelength range. The chip shows low threshold current about 10 mA and stable single mode operation with the side-mode suppression-ratio (SMSR) over 50 dB for all the four channels. 28 Gb/s non-return to zero on-off keying (NRZ-OOK) direct modulation was implemented with clear eye opening and 10 km transmission being demonstrated. These results indicated that the monolithically integrated chip through vertical couplers has the potential for high speed transmission.