Pressure sensor and method of manufacturing the same

A pressure sensor, comprising:

• a reflective movable diaphragm unit comprising diaphragm portions formed by a circular SiO2 film, a mesa portion and light-reflecting mirror portion of the SiO2 film disposed in the center, and a ring-shaped spacer and bonding layer comprising metal layers in the circumferential edge portion of the diaphragm portion;
• a rod lens of a diameter under 125 μm, that consists of a half-mirror layer and a bonding layer at an end surface facing the diaphragm portion;
• and
• an optical fiber with a diameter under b 125 μm.

A method of manufacturing a pressure sensor comprising the following steps:

• depositing a SiO2 layer on a front surface of a silicon substrate and forming a mesa portion by leaving the SiO2 layer in a circular shape;
• depositing a SiO2 layer on a rear surface of a silicon substrate to create a mask that separates a reflective movable diaphragm unit from the silicon substrate;
• further depositing a SiO2 layer on the front surface of the silicon substrate to form the diaphragm portion;
• forming a light-reflecting mirror portion on the mesa portion;
• forming a spacer on a circumferential edge portion of the diaphragm portion and then forming a bonding layer on top;
• separating the reflective movable diaphragm unit from the silicon substrate;
• forming a half mirror layer on a front end of an optical fiber and forming a bonding layer on top of that;
• inserting the reflective movable diaphragm unit into a capillary in a vacuum environment together with an end surface of an optical fiber, and the reflective movable diaphragm unit and optical fiber are attached from the other end by micro beads and another optical fiber, and melting down the bonding layer by heating and fixing the reflective movable diaphragm unit to the top end of the optical fiber;
• and
• removing the optical fiber from the capillary.