Abstract: An optical microcavity device (10), an alignment structure for an optical device, and a method for aligning an optical device are disclosed.

Abstract: A sensor is disclosed, comprising: a first optical reflector provided on a first support element; a second optical reflector provided on a second support element and arranged opposed to the first optical reflector along an optical axis, the opposed first and second optical reflectors being spaced from each other forming a sample space for containing a sample between the first and second optical reflectors; wherein the second optical reflector comprises a recess to provide an optical cavity with stable resonance in at least one mode and having an optical cavity length of at most 50 ?m and/or an optical mode volume of 100 ?m3 or less; at least one electromagnetic (EM) radiation source configured to illuminate the optical cavity with EM radiation; and a detector configured to detect EM radiation from the optical cavity; wherein the first support element and the second support element are bonded to each other and form a unitary structure.