Hybrid erbium-doped DFB waveguide laser made by wafer bonding of two ion-exchanged glasses

Er-doped and Er/Yb-codoped glasses have a key role in the production of lasers and amplifiers for optical communication systems and eye-safe sensors operating at wavelengths around 1550 nm. Ion-exchanged waveguides on Er/Yb-codoped phosphate glass allow implementing quite compact and efficient active devices. Unfortunately, these wafers are not compatible with the integration of passive functions since unpumped erbium ions absorb 1550 nm signal. Hence, an efficient monolithic co-integration of passive and active optical functions requires hybridizing doped and undoped glasses. In this paper, we present the realization of a fully encapsulated three-dimensional distributed feedback (DFB) hybrid laser obtained by the wafer bonding of two ion-exchanged substrates. On the first one, an undoped silicate glass, a selectively buried channel core waveguide is made by a Ag+/Na+ exchange and a field-assisted burial. A Bragg grating is then etched on the wafer surface. On the second wafer, an Er/Yb-codoped phosphate glass, a slab core waveguide is obtained by a Ag+/Na+ exchange. The two wafers are finally bonded together yielding to a DFB laser: the interaction between the guided light and the doped glass provides the amplification, while the Bragg grating supplies the feedback. With this fully encapsulated device, (420±15) µW laser emission has been observed at 1534 nm for (390±20) mW injected pump power, while its input and output are totally insulated from the doped wafer.