Attenuation inner-window in the amplifier- and modulator-integrated laser diode

To better control the input power of an amplifier, which is monolithically integrated with an electroabsorptive-modulated laser, an inner window is implemented by removing a section of the waveguide to realize an attenuator. It also reduces the effect of amplified spontaneous emission on the integrated laser. Attenuation around -10 dB is obtained by adjusting the length of the inner window. Because of different focal depths, unguided stray light from the inner window is not coupled to a fiber on which the amplifier output is focused through a lens.