Koichi Takiguchi
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Fig. 1 Experimental set-up for converting THz-wave signal into optical signal.
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https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-5-6598
A simple method, which converts a high-speed and spectrally efficient on-off keying (OOK) signal in the terahertz (THz)-band into an optical signal, is reported. In the proposed method, the THz-wave signal is down-converted into a radio-frequency (RF) signal, which is transferred to an optical signal through an optical intensity modulator. This modulator’s bias is set to a null point. An extracted optical sideband from the modulator output corresponds to the converted optical signal. When the intermediate frequency (IF) of the RF signal is set to more than or equal to half of the signal bandwidth, the method enables us to carry out proper conversion. The method is adequate for a spectrally efficient signal because the IF can be set to a low value. To show the method’s validity, calculation, and some experiments using a signal shaped with a root Nyquist optical filter were carried out.
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