silicon and lithium-niobate

Electro-optic modulators (EOMs) are indispensable elements for integrated photonic circuits. However, optical insertion losses limit the utilization of EOMs for scalable integration. Here, we propose a novel, to the best of our knowledge, EOM scheme on a heterogeneous platform of silicon- and erbium-doped lithium niobate (Si/Er:LN). In this design, electro-optic modulation and optical amplification are simultaneously employed in phase shifters of the EOM. The excellent electro-optic property of lithium niobate is maintained to achieve ultra-wideband modulation. Meanwhile, optical amplification is performed by adopting the stimulated transitions of erbium ions in the Er:LN, leading to effective optical loss compensation. Theoretical analysis shows that a bandwidth exceeding 170 GHz with a half-wave voltage of 3 V is successfully realized. Moreover, efficient propagation compensation of ∼4 dB is predicted at a wavelength of 1531 nm.

Topics: Erbium; Eye; Oxides; Silicon

Dynamically reconfigurable metasurfaces promise compact and lightweight spatial light modulation for many applications, including LiDAR, AR/VR, and LiFi systems. Here, we design and computationally investigate high-quality-factor silicon-on-lithium niobate metasurfaces with electrically driven, independent control of its constituent nanobars for full phase tunability with high tuning efficiency. Free-space light couples to guided modes within each nanobar via periodic perturbations, generating quality factors exceeding 30,000 while maintaining a bar spacing of <λ/1.5. We achieve nearly 2π phase variation with an applied bias not exceeding ±25 V, maintaining a reflection efficiency above 91%. Using full-field simulations, we demonstrate a high-angle (51°) switchable beamsplitter with a diffracted efficiency of 93% and an angle-tunable beamsteerer, spanning 18-31°, with up to 86% efficiency, all using the same metasurface device. Our platform provides a foundation for highly efficient wavefront-shaping devices with a wide dynamic tuning range capable of generating nearly any transfer function.

Topics: Electricity; Niobium; Oxides; Silicon

We demonstrate error-free 80km transmission by a silicon carrier-depletion Mach-Zehnder modulator at 10Gbps and the power penalty is as low as 1.15dB. The devices were evaluated through the bit-error-rate characterizations under the system-level analysis. The silicon Mach-Zehnder modulator was also analyzed comparatively with a lithium niobate Mach-Zehnder modulator in back-to-back transmission and long-haul transmission, respectively, and verified the negative chirp parameter of the silicon modulator through the experiment. The result of low power penalty indicates a practical application for the silicon modulator in the middle- or long-distance transmission systems.

Topics: Electronics; Equipment Design; Interferometry; Niobium; Optics and Photonics; Oxides; Signal Processing, Computer-Assisted; Silicon; Telecommunications

We report terahertz-wave generation in the wavelength range of 190 - 210 and 457 - 507 microm from forward and backward difference frequency generations, respectively, in a 3.2-cm long multi-grating periodically poled lithium niobate (PPLN) crystal. The grating period of the PPLN crystal varies form 63 to 70 microm in 1-microm increments. The extraordinary refractive index of lithium niobate in the THz-wave range was precisely deduced from the quasi-phase-matching condition of the difference frequency generations.

Topics: Niobium; Optics and Photonics; Oxides; Refractometry; Silicon

We demonstrated a Cherenkov phase-matching method for monochromatic THz-wave generation using the difference frequency generation process with a lithium niobate crystal, which resulted in high conversion efficiency and wide tunability. We successfully generated monochromatic THz waves across the range 0.2-3.0 THz. We obtained efficient energy conversion in the low frequency region below 0.5 THz, and achieved a flat tuning spectrum by varying the pumping wavelength during THz-wave tuning.

Topics: Crystallization; Equipment Design; Niobium; Optics and Photonics; Oxides; Refractometry; Silicon; Transducers

The need for high-frequency, wide-band filters has instigated many developments based on combining thin piezoelectric films and high acoustic velocity materials (sapphire, diamond-like carbon, silicon, etc.) to ease the manufacture of devices operating above 2 GHz. In the present work, a technological process has been developed to achieve thin-oriented, single-crystal lithium niobate (LiNbO3) layers deposited on (100) silicon wafers for the fabrication of radio-frequency (RF) surface acoustic wave (SAW) devices. The use of such oriented thin films is expected to favor large coupling coefficients together with a good control of the layer properties, enabling one to chose the best combination of layer orientation to optimize the device. A theoretical analysis of the elastic wave assumed to propagate on such a combination of material is first exposed. Technological aspects then are described briefly. Experimental results are presented and compared to the state of art.

Topics: Acoustics; Computer Simulation; Crystallization; Equipment Design; Equipment Failure Analysis; Materials Testing; Membranes, Artificial; Models, Theoretical; Niobium; Oxides; Radiation Dosage; Radio Waves; Radiometry; Silicon