An optical device assembly comprising : • a single-mode optical device having an optical axis; • a holder comprising: ∘ a substrate with an upper surface , ∘ two separated walls for securing said optical device , each being attached to said upper surface at one of their ends, so as to define a housing having a longitudinal axis of symmetry , ▪ the dimensions of which are adapted to receive said optical device , ▪ each wall having a locating portion for allowing a bonding element to flow along said locating portion and at least one binding preventing portion for preventing the flowing of said bonding element along said at least one binding preventing portion , said at least one binding preventing portion being located between the substrate and the locating portion , ▪ the locating portion of each wall being disposed facing each other symmetrically with respect to the longitudinal axis of the housing , • the bonding element covering the locating portions of said separated walls , characterised in that a gap is designed between the bottom of the single-mode optical device and the upper surface of the substrate , so that the whole single-mode optical device is remote from the upper surface of the substrate and that no bonding element is flowing in-between. • a single-mode optical device having an optical axis; • a holder comprising: ∘ a substrate with an upper surface , ∘ two separated walls for securing said optical device , each being attached to said upper surface at one of their ends, so as to define a housing having a longitudinal axis of symmetry , ▪ the dimensions of which are adapted to receive said optical device , ▪ each wall having a locating portion for allowing a bonding element to flow along said locating portion and at least one binding preventing portion for preventing the flowing of said bonding element along said at least one binding preventing portion , said at least one binding preventing portion being located between the substrate and the locating portion , ▪ the locating portion of each wall being disposed facing each other symmetrically with respect to the longitudinal axis of the housing , ∘ a substrate with an upper surface , ∘ two separated walls for securing said optical device , each being attached to said upper surface at one of their ends, so as to define a housing having a longitudinal axis of symmetry , ▪ the dimensions of which are adapted to receive said optical device , ▪ each wall having a locating portion for allowing a bonding element to flow along said locating portion and at least one binding preventing portion for preventing the flowing of said bonding element along said at least one binding preventing portion , said at least one binding preventing portion being located between the substrate and the locating portion , ▪ the locating portion of each wall being disposed facing each other symmetrically with respect to the longitudinal axis of the housing , ▪ the dimensions of which are adapted to receive said optical device , ▪ each wall having a locating portion for allowing a bonding element to flow along said locating portion and at least one binding preventing portion for preventing the flowing of said bonding element along said at least one binding preventing portion , said at least one binding preventing portion being located between the substrate and the locating portion , ▪ the locating portion of each wall being disposed facing each other symmetrically with respect to the longitudinal axis of the housing , • the bonding element covering the locating portions of said separated walls , characterised in that a gap is designed between the bottom of the single-mode optical device and the upper surface of the substrate , so that the whole single-mode optical device is remote from the upper surface of the substrate and that no bonding element is flowing in-between. <EOS>