Abstract: A differential mode delay (DMD) measurement system for an optical fiber is provided. The system includes an optical test fiber with a plurality of modes; a single mode light source that provides a continuous light wave signal to a modulator; and a pulse generator that provides an electrical pulse train signal to the modulator and a triggering signal to a receiver. The modulator is configured to generate a modulated optical test signal through the optical fiber based at least in part on the received light wave and pulse train signals, and the receiver is configured to receive the test signal transmitted through the fiber and evaluate the test signal based at least in part on the triggering signal. The system can be employed to create DMD waveform and centroid charts to obtain minEMBc bandwidth information for a fiber within a wavelength range.

Abstract: Methods and apparatus for measuring the modal bandwidth of a multimode optical fiber as a function of wavelength are disclosed. The methods include emitting polarized light from a single-mode fiber, frequency-modulating the single-mode polarized light, and then conditioning the frequency-modulated polarized light to excite multiple modes of the multimode optical fiber. The multimode light transmitted by the multimode optical fiber is detected and analyzed by a network analyzer to determine a bandwidth for at least three different wavelengths. A controller performs a fit to the measured bandwidths using a fitting equation to determine the modal bandwidth as a function of wavelength.

Abstract: Multimode optical fiber systems with adjustable chromatic modal dispersion compensation are disclosed, wherein the system includes a VCSEL light source and primary and secondary optically coupled multimode optical fibers. Because the VCSEL light source has a wavelength spectrum that radially varies, its use with the primary multimode optical fiber creates chromatic modal dispersion that reduces bandwidth. The compensating multimode optical fiber is designed to have a difference in alpha parameter relative to the primary multimode optical fiber of ?0.1?????0.9. This serves to create a modal delay opposite to the chromatic modal dispersion. The compensation is achieved by using a select length of the compensating multimode optical fiber optically coupled to an output end of the primary multimode optical fiber. The compensating multimode optical fiber can be configured to be bend insensitive.

Abstract: Multimode optical fiber systems with adjustable chromatic modal dispersion compensation are disclosed, wherein the system includes a VCSEL light source and primary and secondary optically coupled multimode optical fibers. Because the VCSEL light source has a wavelength spectrum that radially varies, its use with the primary multimode optical fiber creates chromatic modal dispersion that reduces bandwidth. The compensating multimode optical fiber is designed to have a difference in alpha parameter relative to the primary multimode optical fiber of ?0.1?????0.9. This serves to create a modal delay opposite to the chromatic modal dispersion. The compensation is achieved by using a select length of the compensating multimode optical fiber optically coupled to an output end of the primary multimode optical fiber. The compensating multimode optical fiber can be configured to be bend insensitive.

Abstract: A differential mode delay (DMD) measurement system for an optical fiber is provided. The system includes an optical test fiber with a plurality of modes; a single mode light source that provides a continuous light wave signal to a modulator; and a pulse generator that provides an electrical pulse train signal to the modulator and a triggering signal to a receiver. The modulator is configured to generate a modulated optical test signal through the optical fiber based at least in part on the received light wave and pulse train signals, and the receiver is configured to receive the test signal transmitted through the fiber and evaluate the test signal based at least in part on the triggering signal. The system can be employed to create DMD waveform and centroid charts to obtain minEMBc bandwidth information for a fiber within a wavelength range.

Abstract: Methods and apparatus for measuring the modal bandwidth of a multimode optical fiber as a function of wavelength are disclosed. The methods include emitting polarized light from a single-mode fiber, frequency-modulating the single-mode polarized light, and then conditioning the frequency-modulated polarized light to excite multiple modes of the multimode optical fiber. The multimode light transmitted by the multimode optical fiber is detected and analyzed by a network analyzer to determine a bandwidth for at least three different wavelengths. A controller performs a fit to the measured bandwidths using a fitting equation to determine the modal bandwidth as a function of wavelength.

Abstract: Multimode optical fiber systems with adjustable chromatic modal dispersion compensation are disclosed, wherein the system includes a VCSEL light source and primary and secondary optically coupled multimode optical fibers. Because the VCSEL light source has a wavelength spectrum that radially varies, its use with the primary multimode optical fiber creates chromatic modal dispersion that reduces bandwidth. The compensating multimode optical fiber is designed to have a difference in alpha parameter relative to the primary multimode optical fiber of ?0.1?????0.9. This serves to create a modal delay opposite to the chromatic modal dispersion. The compensation is achieved by using a select length of the compensating multimode optical fiber optically coupled to an output end of the primary multimode optical fiber. The compensating multimode optical fiber can be configured to be bend insensitive.

Abstract: According to one embodiment, an optical sensing system may include a gated optical amplifier, one or more triggering devices, and an optical coupler. The gated optical amplifier can receive a pulse signal and transform the pulse signal into an amplified pulse signal having an amplified peak portion. The triggering devices can control the gated optical amplifier such that the gated optical amplifier is in the lossy state while the baseline portion of the pulse signal is transformed and the gated optical amplifier is in the gain state while the peak portion of the pulse signal is transformed. The amplified pulse signal can be transmitted to the sensing optical fiber and a sensed optical signal can be received, when the sensing optical fiber is connected to the optical coupler. Optionally, a second pulse signal and the sensed optical signal can be combined and detected with a coherent balanced detection technique.