A method of making a semiconductor-based optical system, said method comprising the steps of: providing a device substrate having a receiving surface; and assembling a printable semiconductor element on said receiving surface of said substrate via contact printing; wherein said printable semiconductor element comprises a semiconductor structure having a length selected from the range of 100 nm to 1000 microns, a width selected from the range of 100 nm to 1000 microns and a thickness selected from the range of 10 nm to 1000 microns and wherein said printable semiconductor element comprises one or more bridge elements which connected the printable semiconductor element to a substrate such as a mother wafer; characterised in that said contact printing comprises: providing a conformable transfer device having a contact surface; establishing conformal contact between an external surface of said printable semiconductor element and said contact surface of said conformable transfer device, wherein said conformal contact bonds said printable semiconductor element to said contact surface; providing a planarizing layer on said receiving surface of said device substrate; contacting said printable semiconductor element bonded to said contact surface and said receiving surface of said device substrate; embedding at least a portion of said printable semiconductor element in said planarizing layer; and separating said printable semiconductor element and said contact surface of said conformable transfer device, thereby assembling said printable semiconductor element on said receiving surface of said device substrate using said conformable transfer device. providing a device substrate having a receiving surface; and assembling a printable semiconductor element on said receiving surface of said substrate via contact printing; wherein said printable semiconductor element comprises a semiconductor structure having a length selected from the range of 100 nm to 1000 microns, a width selected from the range of 100 nm to 1000 microns and a thickness selected from the range of 10 nm to 1000 microns and wherein said printable semiconductor element comprises one or more bridge elements which connected the printable semiconductor element to a substrate such as a mother wafer; characterised in that said contact printing comprises: providing a conformable transfer device having a contact surface; establishing conformal contact between an external surface of said printable semiconductor element and said contact surface of said conformable transfer device, wherein said conformal contact bonds said printable semiconductor element to said contact surface; providing a planarizing layer on said receiving surface of said device substrate; contacting said printable semiconductor element bonded to said contact surface and said receiving surface of said device substrate; embedding at least a portion of said printable semiconductor element in said planarizing layer; and separating said printable semiconductor element and said contact surface of said conformable transfer device, thereby assembling said printable semiconductor element on said receiving surface of said device substrate using said conformable transfer device. providing a conformable transfer device having a contact surface; establishing conformal contact between an external surface of said printable semiconductor element and said contact surface of said conformable transfer device, wherein said conformal contact bonds said printable semiconductor element to said contact surface; providing a planarizing layer on said receiving surface of said device substrate; contacting said printable semiconductor element bonded to said contact surface and said receiving surface of said device substrate; embedding at least a portion of said printable semiconductor element in said planarizing layer; and separating said printable semiconductor element and said contact surface of said conformable transfer device, thereby assembling said printable semiconductor element on said receiving surface of said device substrate using said conformable transfer device.