Disclosed is an optical transmitter module including a directly modulated laser transmitter based on a directly modulated laser (DML) and an arrayed waveguide grating (AWG) chip that is vertically polished. The directly modulated laser transmitter includes a directly modulated laser chip array including one or more directly modulated laser chips, an impedance matching circuit that allows each of the one or more directly modulated laser chips to operate at a critical speed of 100 Gbps per channel or higher, and a radio frequency-flexible printed circuit board (RF-FPCB) that transmits a radio frequency (RF) modulating signal to the directly modulated laser chip array. The arrayed waveguide grating chip includes an optical waveguides that transfer multi-channel optical signals and a wavelength multiplexer that multiplexes the multi-channel optical signals. The directly modulated laser transmitter and the arrayed waveguide grating chip are spaced apart from each other and are optically coupled in chip-to-chip.