Fiber-optic-taper loop probe for characterizing optical components for transverse optical coupling
A fiber-optic-taper loop probe includes first and second fiber segments, first and second tapering segments, and a center taper segment. In a preferred embodiment, first and second fiber segments are about 125 μm in diameter, and the center taper segment has a substantially constant diameter of about 2-5 μm. The fiber-optic taper forms a loop, the center taper segment remaining substantially straight and opposite the crossing point of the loop. The loop is secured to a support structure to maintain its shape and facilitate positioning relative to an optical component to be tested. The fiber segments may be connected to an optical characterization system including one or more light sources, lasers, detectors, spectrometers, etc. The geometry of the loop enables transverse-optical-coupling of the loop probe with an optical component without undesirable contact between other portions of the loop probe and other portions of the optical component and/or substrate.
1. A method for characterizing an optical component adapted for transverse optical coupling, comprising the steps of:
positioning a fiber-optic-taper loop probe near the optical component so as to enable transverse-transfer of optical power between the loop probe and the optical component, wherein the loop probe comprises an optical fiber having a first fiber segment, a first tapering segment, a center taper segment, a second tapering segment, and a second fiber segment, the optical fiber being formed into a loop with the center taper segment positioned on the loop substantially opposite a crossing point of the loop, and at least one support member secured to the optical fiber at the first fiber segment, the first tapering segment, the second tapering segment, or the second fiber segment, wherein the support member serves to maintain the optical fiber in the loop and enables positioning of the loop probe relative to the optical component for transverse-coupling thereto;
applying an input signal to the optical component, the input signal including i) an optical input signal launched into the optical fiber and transmitted through the loop probe to the optical component, or ii) an electronic input signal applied to the optical component; and
detecting and analyzing an output signal, the output signal including i) an optical output signal transmitted through the optical fiber from the loop probe, or ii) an electronic output signal from the optical component.
2. The method of claim 1 , wherein the support member is secured to a positioner for positioning the loop probe relative to the optical component for transverse-coupling thereto.
3. The method of claim 2 , wherein the positioner includes a three-axis translator.
4. The method of claim 2 , wherein the positioner includes a rotator.
5. The method of claim 1 , wherein the output signal includes an optical output signal arising from the optical component.
6. The method of claim 1 , wherein the input signal includes an optical input signal launched into the optical fiber and transmitted through the loop probe past the optical component.
7. The method of claim 1 , wherein:
the input signal includes an optical input signal launched into the optical fiber and transmitted through the loop probe past the optical component, and
the output signal includes that portion of the optical input signal transmitted through the loop probe past the optical component.
8. The method of claim 1 , wherein the input signal includes an electronic input signal applied to the optical component.
9. A method for characterizing multiple optical components on a common substrate, the optical components being adapted for transverse optical coupling, the method comprising the steps of:
a) positioning a fiber-optic-taper loop probe near a selected optical component so as to enable transverse-transfer of optical power between the loop probe and the selected optical component, wherein the loop probe comprises an optical fiber having a first fiber segment, a first tapering segment, a center taper segment, a second tapering segment, and a second fiber segment, the optical fiber being formed into a loop with the center taper segment positioned on the loop substantially opposite a crossing point of the loop, and at least one support member secured to the optical fiber at the first fiber segment, the first tapering segment, the second tapering segment, or the second fiber segment, wherein the support member serves to maintain the optical fiber in the loop and enables positioning of the loop probe relative to the optical component for transverse-coupling thereto;
b) applying an input signal to the selected optical component, the input signal including i) an optical input signal launched into the optical fiber and transmitted through the loop probe to the optical component, or ii) an electronic input signal applied to the optical component; and
c) detecting and analyzing an output signal, the output signal including i) an optical output signal transmitted through the optical fiber from the loop probe, or ii) an electronic output signal from the optical component;
d) moving the loop probe from the selected optical component to a next optical component, the next optical component thereby becoming the selected optical component; and
e) repeating steps a) through d) for multiple optical components on the substrate.