A system for reducing effects relating to stretching of an optical fiber, the system comprising: an optical source, the optical source outputting an optical signal; a terahertz transmitter optically coupled to the optical source, the terahertz transmitter configured to emit terahertz radiation to a sample when activated by the optical signal; a terahertz receiver optically coupled to the optical source, the terahertz receiver configured to detect terahertz radiation conditioned by the sample; a data acquisition system electrically coupled to the terahertz receiver, wherein the terahertz receiver is configured to generate an electrical signal which can be interpreted, scaled and/or digitized by the data acquisition system and the optical fiber, wherein the optical fiber has a first core and a second core; and the optical fiber has a first end optically coupled to the optical source; the first core of the optical fiber being optically coupled to the terahertz transmitter; and the second core of the optical fiber being optically coupled to the terahertz receiver, wherein the optical fiber carrying the optical signal provided to the terahertz transmitter and terahertz receiver is configured to stretch such that the terahertz receiver is synchronized to the terahertz transmitter by the optical signal, wherein a multiplexer is located optically between the optical source and the optical fiber, the multiplexer being configured to send the optical signal via the first core and the second core of the optical fiber; wherein a demultiplexer is located optically between the optical fiber and the terahertz receiver and terahertz transmitter, the demultiplexer being configured to provide the optical pulse from the first core to the terahertz receiver and provide the optical pulse from the second core to the terahertz transmitter, wherein the optical source further comprises a laser source configured to output optical pulses, wherein an optical splitter is optically located between the laser source and the optical fiber, wherein the optical splitter splits the optical signal into two optic paths along a first optical cable and a second optical cable, and wherein the optical multiplexer takes the optical signals coming from the first optical cable and the second optical cable and couples them into the first core and into the second core within the same optical fiber. an optical source, the optical source outputting an optical signal; a terahertz transmitter optically coupled to the optical source, the terahertz transmitter configured to emit terahertz radiation to a sample when activated by the optical signal; a terahertz receiver optically coupled to the optical source, the terahertz receiver configured to detect terahertz radiation conditioned by the sample; a data acquisition system electrically coupled to the terahertz receiver, wherein the terahertz receiver is configured to generate an electrical signal which can be interpreted, scaled and/or digitized by the data acquisition system and the optical fiber, wherein the optical fiber has a first core and a second core; and the optical fiber has a first end optically coupled to the optical source; the first core of the optical fiber being optically coupled to the terahertz transmitter; and the second core of the optical fiber being optically coupled to the terahertz receiver, wherein the optical fiber carrying the optical signal provided to the terahertz transmitter and terahertz receiver is configured to stretch such that the terahertz receiver is synchronized to the terahertz transmitter by the optical signal, wherein a multiplexer is located optically between the optical source and the optical fiber, the multiplexer being configured to send the optical signal via the first core and the second core of the optical fiber; wherein a demultiplexer is located optically between the optical fiber and the terahertz receiver and terahertz transmitter, the demultiplexer being configured to provide the optical pulse from the first core to the terahertz receiver and provide the optical pulse from the second core to the terahertz transmitter, wherein the optical source further comprises a laser source configured to output optical pulses, wherein an optical splitter is optically located between the laser source and the optical fiber, wherein the optical splitter splits the optical signal into two optic paths along a first optical cable and a second optical cable, and wherein the optical multiplexer takes the optical signals coming from the first optical cable and the second optical cable and couples them into the first core and into the second core within the same optical fiber.