PCT/SG2019/050519 WO 2020/081014 one or more tunable elements of the first further example. [0092] A third further example provides an optical phased array comprising one or more tunable elements of the first further example. [0093] A fourth further example provides a method of fabricating a tunable element for an optical waveguide device, the method comprising: forming a first waveguide section and a third waveguide section from a first material; forming a second waveguide section from a second material; forming at least one layer of cladding material on the second waveguide section; and forming one or more resistive heating pads on top of a layer of cladding material and proximate to the second waveguide section, wherein the second material is more thermo-optically sensitive than the first material. [0094] Any range or device value given herein may be extended or altered without losing the effect sought, as will be apparent to the skilled person. [0095] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. [0096] Any reference to ’an’item refers to one or more of those items. The term ’comprising’ is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements. [0097] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought. [0098] It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention.