Breakthrough in Silicon Based Room Temperature Continuous Wave Topological Dirac Vortex Microcavity Laser

With the explosive growth of data traffic, the market is extremely eager for hybrid photonic integrated circuits that can combine various optical components on a single chip.

Silicon is an excellent material for photonic integrated circuits (PICs), but achieving high-performance laser sources in silicon still poses challenges. The monolithic integration of III-V quantum dot (QD) lasers on silicon is considered a promising strategy to solve this problem.

However, most existing QD microcavity lasers are very sensitive to cavity changes, which fundamentally limits the performance of QD microcavity lasers.

It is reported that in a new paper titled "Room performance continuous wave topological Dirac vortex microcavity lasers on silicon" published in the journal "Light: Science&Applications" recently, a team of scientists led by Professor Sun Xiankai from the Chinese University of Hong Kong, Professor Zhang Zhaoyu from the Chinese University of Hong Kong (Shenzhen), and Dr. Chen Siming from University College London in the UK, The room temperature continuous wave Dirac vortex topology laser with InAs/InGaAs QD material grown on a single chip on coaxial silicon substrate at telecommunication wavelengths has been experimentally demonstrated, achieving breakthroughs in laser technology.

a. Concept diagram of a Dirac vortex topology laser grown epitaxial on silicon substrate. The photonic crystal structure is defined in the active layer and suspended by partially removing the sacrificial layer. b. The oblique view scanning electron microscope image of the realized topological Dirac vortex photonic crystal cavity. Scale: 500 nm. c. Cross section bright field transmission electron microscopy image of the active layer containing four stacked InAs/InGaAs QD layers.

It is reported that the laser has topological robustness and is not affected by external defects and cavity size changes, which is expected to revolutionize the technology of CMOS compatible photonic and optoelectronic systems on chips. This breakthrough may pave the way for the next generation of silicon based PICs with topological robustness and versatility.

The Dirac vortex state is a mathematical analog of the famous Mayorana Fermion (so-called "angel particle") in superconductor electronic systems, and has recently been discovered as a new strategy for tightly and robustly limiting classical waves. This method has significant advantages, such as a larger free spectral range than most existing optical cavities, making it an ideal choice for achieving single-mode surface emitting lasers.

The research team designed and manufactured a Dirac vortex photonic crystal laser using auxiliary orbital degrees of freedom in topological insulators. In this way, they are able to control the near-field of the Dirac vortex cavity to obtain linearly polarized far-field emissions. Then, they observed vertical laser emission from these cavities under continuous wave pumping at room temperature.

Experimental characterization of Dirac vortex topology laser. a. The variation of micro region fluorescence spectrum of Dirac vortex laser with pump power. b. The variation of micro region fluorescence spectral intensity (purple dots) and line width (orange squares) with pump intensity. c. The micro region fluorescence spectrum measured when the pump intensity is 0.395 kW cm-2. d. The variation of laser wavelength (purple dot) with pump intensity. e. The laser spectra of different Dirac vortex lasers indicate that precise regulation can be achieved in the wavelength range of 1300-1370 nm.

The breakthrough achievement of Dirac vortex QD laser is not only expected to become an on chip light source for the next generation of silicon-based photonic integrated circuits, but also opens the door to exploring topological phenomena such as non Hermitian properties, boson nonlinearity, and quantum electrodynamics. This may lead to significant progress in the field of optoelectronics and pave the way for more efficient and powerful communication technologies.

Source: Compiled by Old One