Optical waveguide chip based on erbium-doped lithium niobate and mode-locked laser

Abstract

The invention discloses an optical waveguide chip based on erbium-doped lithium niobate and a mode-locked laser. The chip sequentially comprises a substrate, a silicon dioxide cladding, an erbium-doped lithium niobate film and a radio frequency electrode from bottom to top; the erbium-doped lithium niobate thin film is etched through photoetching, and a ridge-type erbium-doped lithium niobate waveguide is formed; and the radio frequency electrodes are arranged on the two sides of the erbium-doped lithium niobate waveguide in parallel. The erbium-doped lithium niobate thin film is used as the waveguide, the low-noise gain characteristic of the erbium-doped waveguide is reserved, the electro-optical characteristic of the lithium niobate waveguide is introduced, the gain and modulation requirements of the active mode-locked laser are met, and the integrated active mode-locked laser which is low in noise and continuously adjustable in repetition frequency can be achieved in cooperation with direct-current bias. The distance between electrodes is reduced through the ridge-type erbium-doped lithium niobate waveguide, the needed modulation voltage and electric power consumption are reduced, overlapping of signal light and pump light speckles can be increased through strong constraint on the signal light and the pump light speckles, and the pump efficiency is improved.

Description

technical field [0001] The invention relates to a mode-locked laser, in particular to an optical waveguide chip and a mode-locked laser based on erbium-doped lithium niobate. Background technique [0002] Integrated mode-locked lasers have important applications in optical signal processing, optical frequency combs and other fields. Traditional integrated mode-locked lasers are mainly based on III-V semiconductor materials, but the lifetime of the upper-level particles of semiconductor materials is only nanoseconds, resulting in a large noise in the mode-locked pulse signal. In high-precision optical signal processing, optical frequency comb It cannot be applied in occasions that require high noise characteristics of the laser. In contrast, the upper-level particle lifetime of erbium-doped waveguides can reach milliseconds, which can provide gain while ensuring low-noise operation of mode-locked lasers. The team of Professor Ippen from the Massachusetts Institute of Techno...

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Problems solved by technology

However, the waveguide formed by titanium diffusion is very wide, resulting in a large distance between the electrodes. A very high modulation voltage must be applied to generate a strong enough electric field to achieve effective modulation by changing the refractive index of lithium niobate through the electro-optic effect, and the power consumption is very high.

Titanium diffusion waveguide has poor confinement of signal light and pump light mode spots, resulting in poor overlap between the two, low pump efficiency, and high power consumption of pump light

In addition, the pump light input and the signal light output are on the same side, resulting in the need for an additional wavelength division multiplexer to distinguish between the two, increasing the cost

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