Compact 100GBaud driverless thin-film lithium niobate modulator on a silicon substrate

Abstract

Electro-optic (EO) modulators with a high modulation bandwidth are indispensable parts of an optical interconnect system. A key requirement for an energy-efficient EO modulator is the low drive voltage, which can be provided using a standard complementary metal oxide semiconductor circuity without an amplifying driver. Thin-film lithium niobate has emerged as a new promising platform, and shown its capable of achieving driverless and high-speed EO modulators. In this paper, we report a compact high-performance modulator based on the thin-film lithium niobate platform on a silicon substrate. The periodic capacitively loaded travelling-wave electrode is employed to achieve a large modulation bandwidth and a low drive voltage, which can support a driverless single-lane 100Gbaud operation. The folded modulation section design also helps to reduce the device length by almost two thirds. The fabricated device represents a large EO bandwidth of 45GHz with a half-wave voltage of 0.7V. The driverless transmission of a 100Gbaud 4-level pulse amplitude modulation signal is demonstrated with a power consumption of 4.49fj/bit and a bit-error rate below the KP4 forward-error correction threshold of 2.4×10−4.

Breaking the bandwidth limit of a high-quality-factor ring modulator based on thin-film lithium niobate

“…4. Considering the length of the MZI structure, i.e., 2 mm, a V π L of 0.35 V•cm is obtained, which is also close to the simulation results (see Supplementary Note 2), and considerably less than those achieved in conventional MZI modulators based on TFLN [25][26][27][37][38][39] .…”

“…Yet, conventional LN modulators remain bulky and discrete suffered from the low refractive index contrast of a diffusion-based waveguide structure 22 . Recently, thinlm LN (TFLN) emerges as a promising platform for integrated photonic devices using LN [23][24][25][26][27] . The…”

“…etched submicron-sized waveguide on TFLN offers a high refractive index contrast, which leads to demonstrations of EO modulators with footprints shrunk to about one tenth of the conventional ones in bulk LN. The driving voltage of such TFLN-based modulators has also been reduced to <1V, and then can be delivered directly through a CMOS (complementary metal-oxide-semiconductor) circuit without using any microwave ampli er 25,27 . Therefore, the energy consumption of the whole signal transmitter can be largely decreased.…”

“…Despite its great success, a TFLN modulator based on a classic Mach-Zehnder interferometer (MZI) structure is still large usually with a length of several centimeters 27 . To further reduce the size of a modulator, resonant structures can be employed, including Fabry-Pérot cavities 28,29 , photonic crystal cavities 30 , or micro-rings 31 .…”

Beyond 300 Gbps Short-Reach Links Using TFLN MZMs With 500 mVpp and Linear Equalization

“…TFLN has emerged as a promising platform for EO modulators because of its high modulation efficiency, negligible optical insertion loss (~0.3 dB/cm), and low microwave loss [2]; allowing the development of 100 GHz modulators [3,4]. Yet, TFLN's real promise is operating with CMOS-compatible driving levels and dispensing the power-hungry RF driver circuitry from the transmission system [2,[5][6][7]. This is very attractive for DCI applications as it reduces the power consumption considerably.…”