Sometime you just have to be patient and read through the doc. Yes, the is a property for sources array.
Here is how i did and it worked.
this.geocoder = new Search({
container: "addrSearch",
autoSelect: false,
view: this.view,
searchAllEnabled: false,
sources: [
{
locator: new Locator("https://geocode.arcgis.com/arcgis/rest/services/World/GeocodeServer"),
singleLineFieldName: "SingleLine",
outFields: ["Addr_type"],
name: "World GeoCoding Service",
minSuggestCharacters: 3,
autoNavigate: false,
popupEnabled: false,
searchExtent: Extent({
xmin: -8631362.9367,
ymin: 4655884.590300001,
xmax: -8532954.2208,
ymax: 4772527.9208,
spatialReference: { "wkid": 102100 }
}),
placeholder: "Enter a US street address",
resultSymbol:null,
}
]
});
Thanks Robert.