An optical interconnect structure connecting a VCSEL laser or a photodetector to a fiber cable with a 3D polymer waveguide is described. The waveguide has a vertical portion at one end of a horizontal trench portion joined by a 45 degree sidewall. The vertical portion interfaces with VCSEL laser arranged on a flexible circuit board. The other end of the horizontal trench portion connects to a fiber via a mechanical transport connector. The flexible structure also holds driver, receiver, pad, amplifier, RF chip and transmission lines. A method of fabrication includes: patterning a polymer cladding layer into a horizontal trench and a 45 degree side wall by applying multiple exposure techniques; filling horizontal trench and 45 degree side wall cavity to form a core followed by planarizing the core layer to remove excess core; patterning a vertical cavity aligned with the 45 degree side wall to form a reflector.