A waveguide structure for optical coupling, comprising: a first waveguide embedded in a cladding of a lower refractive index than the first waveguide , a second waveguide of a higher refractive index than the cladding , and an intermediate waveguide , wherein the first waveguide and the second waveguide are arranged at the same side of the intermediate waveguide to establish an optical coupling between the first waveguide and the second waveguide through only the intermediate waveguide , wherein the first waveguide material has a refractive index value smaller than or equal to 3; wherein relevant wavelength ranges in which the waveguide structure operates are either: the O-band with a range from 1260 nm to 1360 nm, the C- band with a range from 1520 nm to 1570 nm, and/or L-band with a range from 1570 nm to 1610 nm, wherein the waveguide structure is an integrated photonic circuit, wherein the intermediate waveguide comprises two tapered ends (104e1,104e2) and a middle section , the waveguide structure for optical coupling being characterised in that the first waveguide , the second waveguide and the intermediate waveguide each comprise a tapered end (101e, 103e, 104e1, 104e2), a tapered end of the first waveguide being arranged to face a first tapered end (104e1) of the intermediate waveguide for establishing an optical coupling between the first waveguide and the intermediate waveguide ; a second tapered end (104e2) of the intermediate waveguide being arranged to face a tapered end of the second waveguide for establishing an optical coupling between the intermediate waveguide and the second waveguide ; and the middle section of the intermediate waveguide is formed as a bend. a first waveguide embedded in a cladding of a lower refractive index than the first waveguide , a second waveguide of a higher refractive index than the cladding , and an intermediate waveguide , wherein the first waveguide and the second waveguide are arranged at the same side of the intermediate waveguide to establish an optical coupling between the first waveguide and the second waveguide through only the intermediate waveguide , wherein the first waveguide material has a refractive index value smaller than or equal to 3; wherein relevant wavelength ranges in which the waveguide structure operates are either: the O-band with a range from 1260 nm to 1360 nm, the C- band with a range from 1520 nm to 1570 nm, and/or L-band with a range from 1570 nm to 1610 nm, wherein the waveguide structure is an integrated photonic circuit, wherein the intermediate waveguide comprises two tapered ends (104e1,104e2) and a middle section , the waveguide structure for optical coupling being characterised in that the first waveguide , the second waveguide and the intermediate waveguide each comprise a tapered end (101e, 103e, 104e1, 104e2), a tapered end of the first waveguide being arranged to face a first tapered end (104e1) of the intermediate waveguide for establishing an optical coupling between the first waveguide and the intermediate waveguide ; a second tapered end (104e2) of the intermediate waveguide being arranged to face a tapered end of the second waveguide for establishing an optical coupling between the intermediate waveguide and the second waveguide ; and the middle section of the intermediate waveguide is formed as a bend. <EOS>