Structure and method for manufacturing compact optical power monitors of highly reliable performance

Abstract

A new low-cost, highly reliable and compact optical power monitor is manufactured with simplified structure and improved configurations that require only lateral position adjustment for input/output beam alignment. A compact size is achieved by employing prefabricated housing containing a highly effective focus lens placed at fixed position relative to an optical sensor, e.g., a photodiode. The prefabricated housing further function as a seal housing for direct plugging into a holding tube fitting seamlessly to a GRIN lens to focus the tapped collimated beam to the photo sensor thus greatly simplify the manufacturing processes without alignment requirements. Thermal stability and reliable performance is achieved by applying multiple-layered optical reflection-transmission coating directly onto the end surface of a GRIN lens for tapping a small portion of the collimated beam onto the focus lens and the photo sensor. The insertion loss can be conveniently minimized by laterally shifting the relative position of a dual fiber ferrule and the GRIN lens without complicate angular adjustments. A power monitor with compact size, high damage threshold, low manufacture cost and high performance stability is provided for convenient implementation in new and existing optical systems.