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Chip-Scale Lasers: From Biosensing to Underwater Lidar and Quantum Optics

Introduction:

In the world of photonics, chip-scale lasers have emerged as powerful tools, revolutionizing a wide range of applications. These compact light sources have paved the way for remarkable advancements in biosensing, underwater Lidar, and quantum optics. In this blog article, we will explore how chip-scale lasers are transforming these fields and pushing the boundaries of what is possible.

 

As technologies keep advancing at exponential rates and demand for new devices rises accordingly, miniaturizing systems into chips has become increasingly important. Microelectronics has changed the way we manipulate electricity, enabling sophisticated electronic products that are now an essential part of our daily lives.

 

Rise of Integrated photonic circuits and Silocn Photonics

Today, CMOS nano electronics integrated circuits comprise the majority of information processing systems. Silicon  has long been the primary material to develop microelectronic circuits due to its unmatched electronic, mechanical and thermal properties and its abundance on earth’s crust (27.7%). Accordingly, the semiconductor industry, and the Complementary Metal-Oxide Semiconductor (CMOS) technology in particular, has experienced astounding progress in the last 60 years since the first demonstration of a working silicon integrated circuit.

 

Similarly, integrated photonics has been revolutionizing the way we control light for applications such as data communications, imaging, sensing, and biomedical devices. By routing and shaping light using micro- and nanoscale components, integrated photonics shrinks full optical systems into the size of tiny chips.

 

Silicon photonics refers to the application of photonic systems using silicon as  a medium for optical signal transmission . The silicon material used in such photonic systems is designed with sub micrometer precision and is deployed into the microphotonic components. Silicon photonics combines technologies such as complementary metal oxide semiconductor (CMOS), micro-electro-mechanical systems (MEMS) and 3D Stacking.

 

Wide-spread adoption of silicon photonics has been hampered in part by the lack of monolithically integrated laser sources. Whilst there has been a range of microminiature lasers incorporated directly into silicon over the years, including melding germanium-tin lasers with a silicon substrate and using gallium-arsenide (GaAs) to grow laser nanowires, these methods have involved compromise.

 

The ultimate physical manifestation of the silicon photonic device would be as part of an optoelectronic integrated circuit (OEIC) formed monolithically in silicon, combining the photonic functionality and the electronic intelligence in seamless integration.  This requires realization of integrated photonic circuits that  integrates a laser source, couplers, power dividers, modulators, optical multiplexer/demultiplexers, phase rotators, and attenuators giving a designer the ability to create the entire transmit and receive optical system within a single IC. The number of assembly steps are dramatically reduced with SiPh devices and, therefore, so is manufacturing time and production cost.

 

Chip-scale lasers

Despite its success, integrated photonics has been missing a key component to achieve complete miniaturization: high-performance chip-scale lasers. While some progress has been done on near-infrared lasers, the visible-light lasers that currently feed photonic chips are still benchtop and expensive. Since visible light is essential for a wide range of applications including quantum optics, displays, and bioimaging, there is a need for tunable and narrow-linewidth chip-scale lasers emitting light of different colors.

 

Chip-scale lasers are compact and small laser devices that are integrated onto a single semiconductor chip, resulting in a compact size that is much smaller than traditional laser systems. These lasers offer advantages in terms of cost, reliability, and ease of integration with other electronic components. They are used in various applications including telecommunications, data storage, medical devices, and industrial manufacturing.

 

Additionally, chip-scale lasers have a lower power consumption compared to traditional laser systems and can be designed for specific wavelength ranges, making them suitable for a variety of applications. They can be fabricated using well-established semiconductor manufacturing processes, making them cost-effective and scalable. The miniaturization of these lasers also allows for increased integration with other optical components, leading to the development of compact, integrated optical systems. With ongoing advancements in semiconductor technology, chip-scale lasers are expected to play a significant role in the future of photonics and optical communication.

 

Another important feature of chip-scale lasers is their ability to operate at high speeds, making them suitable for use in high-speed optical communication systems. They are also capable of emitting light in the near-infrared range, which is important for various applications, such as optical sensing and spectroscopy. Chip-scale lasers have also been used in sensing applications, where they can be used to detect and measure physical parameters, such as temperature, pressure, and strain.

 

In conclusion, chip-scale lasers are a promising technology that offer a number of advantages over traditional laser systems. Their compact size, low power consumption, and high-speed operation make them suitable for use in a wide range of applications, from telecommunications to medical devices and industrial manufacturing. With ongoing advancements in semiconductor technology, it is expected that chip-scale lasers will continue to play a significant role in the future of photonics and optical communication.

For deeper understanding of Chip-scale laser technology and applications please visit: Tunable and narrow linewidth chip-scale lasers

Tunable and narrow linewidth chip-scale lasers are compact laser devices that can be adjusted to emit light at different wavelengths and with a narrow range of frequencies. This makes them suitable for various applications that require precise control of the optical frequency, such as spectroscopy, optical sensing, and optical communication systems.

In comparison to traditional laser systems, tunable and narrow linewidth chip-scale lasers offer several advantages. They are compact, low-power, and can be integrated with other optical components, allowing for the development of compact, integrated optical systems. Furthermore, their compact size and low-power consumption make them suitable for portable and battery-powered applications.

To achieve tunability and narrow linewidth, various techniques can be employed, such as the use of electro-optic modulators, thermo-optic modulators, and micro-electromechanical systems (MEMS). These technologies allow for precise control of the laser frequency, making them ideal for applications that require highly stable and accurate laser sources.

In conclusion, tunable and narrow linewidth chip-scale lasers are a promising technology for various applications that require precise control of the optical frequency. Their compact size, low-power consumption, and the ability to integrate with other optical components make them suitable for use in a wide range of applications, from spectroscopy to optical communication systems.

 

Biosensing: Revolutionizing Healthcare and Biomedical Research

Chip-scale lasers have played a pivotal role in biosensing, enabling breakthroughs in healthcare and biomedical research. With their compact size and high sensitivity, these lasers have enabled the development of portable, point-of-care diagnostic devices. From monitoring vital signs to detecting biomarkers, chip-scale lasers have made healthcare more accessible and efficient. They have also contributed to advancements in genomics, proteomics, and drug discovery, empowering researchers with precise tools for understanding and combating diseases.

Underwater Lidar: Illuminating the Depths

Underwater Lidar, a technology for mapping and imaging underwater environments, has greatly benefited from chip-scale lasers. Traditionally, underwater surveys and inspections posed challenges due to limited visibility. However, chip-scale lasers have provided a solution by enabling compact and efficient laser sources for underwater Lidar systems. These lasers generate high-intensity beams that penetrate the water and illuminate submerged objects with exceptional clarity. Applications range from underwater archaeology and marine exploration to environmental monitoring and offshore infrastructure inspection.

Quantum Optics: Unleashing the Power of Quantum Technologies

Quantum optics, a field at the forefront of quantum technologies, has experienced a paradigm shift with the advent of chip-scale lasers. These lasers have enabled precise control and manipulation of quantum states, facilitating groundbreaking advancements in quantum computing, quantum communication, and quantum metrology. By integrating chip-scale lasers with other quantum systems, such as quantum dots or superconducting circuits, researchers have unlocked new possibilities for harnessing the principles of quantum mechanics. Chip-scale lasers have accelerated the development of practical quantum technologies, bringing us closer to the era of quantum supremacy.

 

Columbia Engineering researchers have invented the first tunable and narrow linewidth chip-scale lasers for visible wavelengths shorter than red

Researchers at Columbia Engineering’s Lipson Nanophotonics Group have created visible lasers of very pure colors from near-ultraviolet to near-infrared that fit on a fingertip. The colors of the lasers can be precisely tuned and extremely fast – up to 267 petahertz per second, which is critical for applications such as quantum optics. The team is the first to demonstrate chip-scale narrow-linewidth and tunable lasers for colors of light below red — green, cyan, blue, and violet. These inexpensive lasers also have the smallest footprint and shortest wavelength (404 nm) of any tunable and narrow-linewidth integrated laser emitting visible light. The study, which was first presented at the CLEO 2021 post-deadline session on May 14, 2021, was published online December 23, 2022, by Nature Photonics.

Benefits of emitting wavelengths below red

The importance of lasers emitting wavelengths shorter than red is clear when you consider some important applications. Displays, for example, require red, green, and blue light simultaneously to compose any color. In quantum optics, green, blue, and violet lasers are used for trapping and cooling atoms and ions. In underwater Lidar (Light Detection and Ranging), green or blue light is needed to avoid water absorption. However, at wavelengths shorter than red, the coupling and propagation losses of photonic integrated circuits increase significantly, which has prevented the realization of high-performance lasers at these colors.

Solving coupling and propagation loss issues

The researchers solved the coupling loss problem by choosing Fabry-Perot (FP) diodes as the light sources, which minimizes the impact of the losses on the performance of the chip-scale lasers. Unlike other strategies that use different types of sources, the team’s approach enables the realization of lasers at record-short wavelengths (404 nm) while also providing scalability to high optical powers, FP laser diodes are inexpensive and compact solid-state lasers widely used in research and industry. However, they emit light of several wavelengths simultaneously and are not easily tunable, preventing them to be directly used for applications requiring pure and precise lasers. By combining them with the specially designed photonic chip, the researchers are able to modify the laser emission to be single-frequency, narrow-linewidth, and widely tunable.

The team overcame the propagation loss issue by designing a platform that minimizes both the material absorption and surface scattering losses simultaneously for all the visible wavelengths. To guide the light, they used silicon nitride, a dielectric widely used in the semiconductor industry that is transparent for visible light of all colors. Even though there is minimal absorption, the light still experiences loss due to unavoidable roughness from the fabrication processes. The team solved this problem by designing a photonic circuit with a special type of ring resonator. The ring has a variable width along its circumference, allowing for single-mode operation characteristic of narrow waveguides, and low loss characteristic of wide waveguides. The resulting photonic circuit provides a wavelength-selective optical feedback to the FP diodes that forces the laser to emit at a single desired wavelength with very narrow linewidth.

“By combining these intricately designed pieces, we were able to build a robust and versatile platform that is scalable and works for all colors of light,” said Corato Zanarella.

Revolutionizing technologies

“As a laser manufacturer we recognize that integrated photonics will have a tremendous impact on our industry and will enable a new generation of applications that have so far been impossible,” said Chris Haimberger, Director of Laser Technology, TOPTICA Photonics, Inc. “This work represents an important step forward in the pursuit of compact and tunable visible lasers that will power future developments in computing, medicine, and industry.” 

The study’s findings could revolutionize a broad range of applications, including:

  • Quantum information. Most quantum bits for quantum computation use atoms or ions that are trapped and probed using visible light. The light must be very pure (narrow linewidth) and have very specific wavelengths to address atomic transitions. Currently, the lasers available for these applications are expensive and benchtop. This new study shows that these bulky sources can be replaced by tiny and inexpensive chips, which will enable quantum systems to be scaled down and eventually become part of technologies accessible by the general public.
  • Atomic Clocks. The most precise clocks are based on strontium atoms, which need to be trapped and probed by lasers of many different colors at the same time. Similarly to quantum optics systems, the massive size of the currently available lasers confines this technology to research labs. The chip-scale lasers will make it possible to shrink these systems with the goal of making portable atomic clocks.
  • Biosensing. Several neural probes use a technology called optogenetics to measure, modify, and understand the neural response. In this technology, neurons are genetically modified to produce a type of protein called opsin that is sensitive to visible light. By shining visible light, typically blue, into these cells, scientists can turn on specific neurons at will. Similarly, in fluorescent imagining, fluorophores need to be excited with visible light in order to generate the desired images. These high-performance, compact lasers open the doors for miniaturizing these systems.
  • Underwater ranging. Underwater ranging requires blue or green light because ocean water strongly absorbs light of all the other colors. In addition, for the popular ranging strategy called Frequency-Modulated Continuous Wave LiDAR, the laser needs to be speedily tunable for accurate sensing of the distance and velocity of objects. These lasers could be used for portable underwater ranging systems employing this technology.
  • Li-Fi. As the demand for bandwidth in communication systems increases, networks have become saturated. Li-Fi, or visible light communications, is a rapidly growing technology that promises to supplement the traditional microwave links at the user end to overcome this bottleneck. The high modulation speeds of the lasers are ideal for enabling extremely fast optical wireless communication links.

Next steps

The researchers, who have filed a provisional patent for their technology, are now exploring how to optically and electrically package the lasers to turn them into standalone units and use them as sources in chip-scale visible light engines, quantum experiments, and optical clocks.

“In order to move forward, we have to be able to miniaturize and scale these systems, enabling them to eventually be incorporated in mass-deployed technologies,” said Lipson, a pioneer in silicon photonics whose research has strongly shaped the field from its inception decades ago, with foundational contributions in the active and passive devices that are part of any current photonic chip. She added, “Integrated photonics is an exciting field that is truly revolutionizing our world, from optical telecommunications to quantum information to biosensing.”

 

Conclusion:

Chip-scale lasers have emerged as key enablers in the fields of biosensing, underwater Lidar, and quantum optics. Their compact size, efficiency, and versatility have revolutionized healthcare, underwater exploration, and quantum technologies. With the potential to make diagnostics more accessible, illuminate the depths of our oceans, and unlock the power of quantum computing, chip-scale lasers are propelling us into a future filled with endless possibilities.

As researchers and engineers continue to innovate in chip-scale laser technology, we can anticipate even more remarkable applications and advancements. The convergence of biosensing, underwater Lidar, and quantum optics holds tremendous potential for transforming industries, improving lives, and unraveling the mysteries of the universe. Exciting times lie ahead as chip-scale lasers continue to push the boundaries of what is possible in these fascinating fields.

 

References and Resources also include:

https://www.eurekalert.org/news-releases/975662

About Rajesh Uppal

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