This paper presents an all-fiber, fully-optically controlled, optical-path length modulator based on highly absorbing optical fiber. The modulator utilizes a high-power 980 nm pump diode and a short section of vanadium-co-doped single mode fiber that is heated through absorption and a non-radiative relaxation process. The achievable path length modulation range primarily depends on the pumpćs power and the convective heat-transfer coefficient of the surrounding gas, while the time response primarily depends on the heated fiberćs diameter. An absolute optical length change in excess of 500 m and a time-constant as short as 11 ms, were demonstrated experimentally. The all-fiber design allows for an electrically-passive and remote operation of the modulator. The presented modulator could find use within various fiber-optics systems that require optical (remote) path length control or modulation.
COBISS.SI-ID: 16870678
This paper presents a miniature, high-sensitive, all-silica Fabry-Perot fiber optic sensor suitable for simultaneous measurements of pressure and temperature. The proposed sensor consists of two low fines Fabry-Perot resonators, created at the tip of an optical fiber. The first resonator is embodied in the form of a short air cavity positioned at the tip of the fiber. This resonator utilizes a thin silica diaphragm to achieve the sensor’s pressure response. The second resonator exploits the refractive index-dependence of silica fiber in order to provide the proposed sensor’s temperature measurement function. Both resonators have substantially different lengths that permit straightforward spectrally-resolved signal-processing and unambiguous determination of the applied pressure and temperature.
COBISS.SI-ID: 16108822
This paper presents a maskless micromachining process that can reform or reshape a section of an optical fiber into a complex 3-D photonic microstructure. This proposed micromachining process is based on the etching rate control achieved by the introduction of phosphorus pentoxide into silica glass through standard fiber manufacturing technology. Regions within a fiber cross section doped with phosphorus pentoxide can etch up to 100 times faster than pure silica when exposed to hydrofluoric acid. Various new photonic devices can be effectively and economically created by design and production of purposely doped fibers that are spliced at the tip or in-between standard lead-in fibers, followed by etching into a final structure.
COBISS.SI-ID: 15204374
This paper presents an optical fiber-field access device suitable for use in different in-line fiber-opticsć systems and fiber-based photonicsć components.The proposed device utilizes a thin silica micro-wire positioned in-between two lead-in single mode fibers. The thin micro-wire acts as a waveguide that allows for low-loss interconnection between both lead-in fibers, while providing interaction between the guided optical field and the surrounding medium or other photonic structures. The field interaction strength, total loss, and phase matching conditions can be partially controlled by device-design. The presented all-fiber device is miniature in size and utilizes an all-silica construction. It has mechanical properties suitable for handling and packaging without the need for additional mechanicalsupport or reinforcements. The proposed device was produced using a micromachining method that utilizes selective etching of a purposely-produced phosphorus pentoxide-doped optical fiber. This method is simple, compatible with batch processes, and has good high-volume manufacturing potential.
COBISS.SI-ID: 16494870
This letter presents a refractive index sensor created at the tip of an optical fiber that utilizes silica nanowire within a radius of between 225 nm and 600 nm, as a sensing element. Sensitivity in excess of 800 nm/RIU was demonstrated within an aquatic medium, while the entire sensor structure was shorter than 1mm with a diameter equal to or less than the standard fiber diameter. The presented sensor structure is made entirely from silica and provides the mechanical protection of sensitive nanowire. The proposed sensor is thus a robust and self-sustained structure, which does not require any complex packing.
COBISS.SI-ID: 16918038