Ultrafast tunable photonic integrated Pockels extended-DBR laser

TL;DR

This paper introduces a simple, tunable, and high-power Pockels-effect laser using an extended DBR architecture on a LNOI platform, enabling fast, linear, and stable frequency tuning for advanced optical applications.

Contribution

It presents a novel extended DBR laser design that achieves wide, linear, and stable frequency tuning with high output power, controlled by a single analog input, overcoming previous limitations of microresonator-based Pockels lasers.

Findings

Over 10 GHz continuous tuning range with flat actuation bandwidth up to 10 MHz.

Achieved over 15 mW in-fiber output power at 1545 nm.

Demonstrated effective use in FMCW LiDAR and gas spectroscopy.

Abstract

Frequency-agile lasers that can simultaneously feature low noise characteristics as well as fast mode hop-free frequency tuning are keystone components for applications ranging from frequency modulated continuous wave (FMCW) LiDAR, to coherent optical communication and gas sensing. The hybrid integration of III-V gain media with low-loss photonic integrated circuits (PICs) has recently enabled integrated lasers with faster tuning and lower phase noise than the best legacy systems, including fiber lasers. In addition, lithium niobate on insulator (LNOI) PICs have enabled to exploit the Pockels effect to demonstrate self-injection locked hybrid lasers with tuning rates reaching peta-hertz per second. However, Pockels-tunable laser archetypes relying on high-Q optical microresonators have thus far only achieved limited output powers, are difficult to operate and stabilize due to the dynamics of self-injection locking, and require many analog control parameters. Here, we overcome this challenge by leveraging an extended distributed Bragg reflector (E-DBR) architecture to demonstrate a simple and turn-key operable frequency-agile Pockels laser that can be controlled with single analog operation and modulation inputs. Our laser supports a continuous mode hop-free tuning range of over 10 GHz with good linearity and flat actuation bandwidth up to 10 MHz, while achieving over 15 mW in-fiber output power at 1545 nm and kHz-level intrinsic linewidth, a combination unmet by legacy bulk lasers. This hybrid laser design combines an inexpensive reflective semiconductor optical amplifier (RSOA) with an electro-optic DBR PIC manufactured at wafer-scale on a LNOI platform. We showcase the performance and flexibility of this laser in proof-of-concept coherent optical ranging (FMCW LiDAR) demonstration, achieving a 4 cm distance resolution and in a hydrogen cyanide spectroscopy experiment.