Assembly comprising a quantum cascade laser, and an associated base, the quantum cascade laser comprising: - an insulating substrate, - at least one semiconductor waveguide formed by etching of layers epitaxied onto the insulating substrate, protruding from the insulating substrate, and having a quantum cascade structure, said semiconductor waveguide forming a gain zone, - an upper electric contact disposed according to a length of the semiconductor wave guide, - at least one lateral electric contact (14, 15) disposed according to a length of the insulating substrate at a distance from the upper electric contact, - the base comprising: - a thermally conductive and electrically insulating matrix, - a central electric contact disposed according to a length of the matrix, - at least one lateral electric contact (24, 25) disposed at a distance from the central electric contact disposed according to a length of the matrix, the assembly being characterised in that the thermally conductive and electrically insulating matrix is structured in such a way as to conform to the shape of the waveguide of the laser and the shape of the insulating substrate in order for: - the upper electric contact of the laser to be in contact with the central electric contact of the base over the length of the matrix, - the lateral electric contact (14, 15) of the laser to be in contact with the lateral electric contact (24, 25) of the base. - an insulating substrate, - at least one semiconductor waveguide formed by etching of layers epitaxied onto the insulating substrate, protruding from the insulating substrate, and having a quantum cascade structure, said semiconductor waveguide forming a gain zone, - an upper electric contact disposed according to a length of the semiconductor wave guide, - at least one lateral electric contact (14, 15) disposed according to a length of the insulating substrate at a distance from the upper electric contact, - the base comprising: - a thermally conductive and electrically insulating matrix, - a central electric contact disposed according to a length of the matrix, - at least one lateral electric contact (24, 25) disposed at a distance from the central electric contact disposed according to a length of the matrix, the assembly being characterised in that the thermally conductive and electrically insulating matrix is structured in such a way as to conform to the shape of the waveguide of the laser and the shape of the insulating substrate in order for: - the upper electric contact of the laser to be in contact with the central electric contact of the base over the length of the matrix, - the lateral electric contact (14, 15) of the laser to be in contact with the lateral electric contact (24, 25) of the base. - a thermally conductive and electrically insulating matrix, - a central electric contact disposed according to a length of the matrix, - at least one lateral electric contact (24, 25) disposed at a distance from the central electric contact disposed according to a length of the matrix, - the upper electric contact of the laser to be in contact with the central electric contact of the base over the length of the matrix, - the lateral electric contact (14, 15) of the laser to be in contact with the lateral electric contact (24, 25) of the base.