Development of lumped constant type LN optical modulators operating at 10GHz band

In order to create a lumped-constant LN (LiNbO₃) optical modulator that operates with high sensitivity in the 7-10 GHz band, it is necessary to ascertain the impact of the electrode pad capacitance, lead inductance, and other factors. An electromagnetic-field simulator has thus shown that the width of the LN crystal substrate is the main impediment to achieving high frequency and sensitivity; based on this result, we created four prototype 10-GHz band lumped-constant LN optical modulators, and evaluated their performance. As a result, we measured a resonant frequency of about 10.1GHz with an LN crystal substrate that was 1.4 mm wide and 0.3 mm thick, and achieved a 20dB CNR. This provided an optimistic outlook on the possibility of achieving a high-sensitivity LN optical modulator operating in the 10 GHz band, which is the highest allocated frequency range.