Interdisciplinary Advances in Microcombs: Bridging Physics and Information Technology

Information Science Engineering Optics Quantum Physics Electrical Engineering Materials Science Electronic Information Physics Semiconductors and Information Devices
microcombs optical frequency combs information science quantum optics optical communications

Interdisciplinary Advances in Microcomb Technology: Bridging Physics and Information Technology

Academic Background

The optical frequency comb (OFC) is a technology that divides the optical frequency domain into a series of discrete, equally spaced frequency lines. It has been widely used in precision measurements, optical communications, atomic clocks, and quantum information. However, traditional frequency comb devices are typically bulky and complex, making it difficult to meet modern scientific and technological demands for portability and integration. In recent years, microcomb technology has garnered significant attention due to its compactness, high efficiency, and versatility. Microcombs, generated based on nonlinear effects in optical microcavities, can achieve frequency comb functions at the chip level, thus bringing revolutionary changes to multiple fields.

Despite significant progress in microcomb technology, further exploration is still needed regarding material selection, generation mechanisms, functional optimization, and practical application potential. To systematically summarize the latest advances in microcomb technology and look forward to its future development direction, the authors of this paper have written a review article aimed at comprehensively exploring the interdisciplinary frontiers of microcomb technology from physical principles to practical applications.

Paper Source

This review article was co-first-authored by Bai-Cheng Yao and Wen-Ting Wang, with Chee Wei Wong and Bai-Cheng Yao serving as corresponding authors. The authors come from the following institutions: - Key Laboratory of Optical Fibre Sensing and Communications, University of Electronic Science and Technology of China - Communication and Integrated Photonics Laboratory, Xiong’an Institute of Innovation, Chinese Academy of Sciences - National Laboratory of Solid State Microstructures and School of Electronic Science and Engineering, Nanjing University - Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles

The paper was published in the open-access journal eLight in 2024, with the DOI 10.1186/s43593-024-00071-9.

Main Content

1. Latest Advances in Microcomb Generation and Functionalization

Material Platforms

The core of microcomb technology lies in the design and fabrication of optical microcavities, where material selection directly affects performance. The authors discuss in detail various materials and their applications in microcomb generation: - Silicon Dioxide (SiO₂): Known for its wide transparency window and low loss characteristics but requires high input power or high Q-factor to compensate for its lower nonlinearity coefficient. - Fluorides (e.g., MgF₂): Possess extremely low optical losses and ultra-high quality factors (Q > 10⁸), making them suitable for efficient frequency comb generation. - Silicon Nitride (Si₃N₄): Combines high nonlinearity coefficients with CMOS compatibility and is one of the most commonly used materials for chip-scale microcavities. - Aluminum Nitride (AlN): Notable for its high thermal conductivity and piezoelectric tunability, making it particularly suitable for dynamic feedback control. - Lithium Niobate (LiNbO₃): Due to its significant second- and third-order nonlinear effects, it has become an ideal candidate for broadband frequency comb generation.

Additionally, emerging materials such as silicon carbide, two-dimensional materials, and halide perovskites also show great potential.

Generation Methods

Microcomb generation relies on nonlinear optical effects, mainly including the following mechanisms: - Kerr Effect: Broadband frequency combs are generated through cavity-enhanced four-wave mixing (FWM). - Laser Gain: Frequency combs are directly generated using materials with gain properties. - Electro-Optic Modulation: Frequency combs are generated by driving microcavities with external modulators. - Multi-Effect Coupling: More complex frequency comb generation is achieved by combining various nonlinear effects (such as Raman scattering and Brillouin scattering).

Each method has its unique advantages. For example, Kerr-effect microcombs can be stably generated using auxiliary laser heating strategies, while electro-optic modulation methods provide flexible and controllable comb tooth spacing.

Functional Optimization

To enhance the performance of microcombs, researchers have developed various functional optimization strategies: - Bandwidth Expansion: Achieved through dispersion management or introducing auxiliary pump lasers to extend spectral width. - Efficiency Improvement: Using dark-pulse mode-locking or dual-cavity coupling to recycle pump energy to improve conversion efficiency. - Dynamic Control: Regulating microcomb repetition rates, spectral ranges, and other parameters using electro-optic effects, mechanical stress, or temperature control.

These optimization techniques not only improve the performance of microcombs but also lay the foundation for their applications in different fields.

2. Applications of Microcombs in Information Science

Signal Generation and Synchronization

As an efficient electromagnetic wave oscillation source, microcombs can be used to generate continuous wave signals in the millimeter to terahertz bands. Combined with optical frequency division (OFD) technology, microcombs can achieve ultra-low noise microwave signal generation, providing support for communication and radar navigation systems.

Data Transmission

Microcombs show great potential in optical communications, especially in wavelength division multiplexing (WDM) systems. By generating hundreds of stable carrier channels, microcombs can significantly increase data transmission capacity. For example, research has achieved data transmission rates exceeding 50 Tbit/s while maintaining a bit error rate below 10⁻³.

Quantum Information Processing

As a quantum light source, microcombs can be used to generate entangled photon pairs or multi-wavelength quantum states. Research based on lithium niobate microcavities shows that microcombs can generate high-quality entangled photon sources, providing new tools for quantum key distribution and quantum network construction.

3. Applications of Microcombs in Information Acquisition

Spectroscopy

Dual-comb spectroscopy (DCS) uses two slightly different frequency combs for interferometric measurements, enabling real-time detection without bulky mechanical spectrometers. The miniaturization and high coherence of microcombs make them ideal for DCS, achieving breakthroughs in gas sensing and molecular identification.

LiDAR and Imaging

Microcomb technology also excels in the field of Light Detection and Ranging (LiDAR). Through time-of-flight (ToF) or frequency-modulated continuous wave (FMCW) methods, microcombs can achieve rapid and precise three-dimensional distance measurements, supporting autonomous driving and remote sensing.

Research Significance and Value

This paper comprehensively summarizes the latest advances in microcomb technology, from material platforms to generation mechanisms, to functional optimization and practical applications, showcasing its broad prospects in information science. Microcombs not only promote the development of classical and quantum information science but also bring new possibilities to precision measurement, communication technology, and environmental monitoring. In the future, with advances in material engineering and integration technology, microcombs are expected to transition from the laboratory to large-scale commercial applications, becoming an important cornerstone of next-generation information technology.

Research Highlights

  1. Interdisciplinary Integration: Microcomb technology connects physics, materials science, and information technology, demonstrating the synergistic effects of scientific research.
  2. Technological Innovation: The introduction of new materials and generation methods has significantly improved the performance of microcombs.
  3. Wide Application: From communication to quantum computing, the application scenarios of microcombs continue to expand, highlighting their versatility.

This article points the way for the future development of microcomb technology and also provides valuable reference resources for researchers in related fields.