Even if a laser is designed to emit purely in one wavelength, changes in temperature and other environmental factors often introduce noise that causes the light emission to shift or broaden in frequency. The broadened spectral extent of this emission is known as the laser linewidth. The researchers used a new approach to create an optical fiber laser with a spectral linewidth narrower than ever achieved by a fiber or semiconductor laser. The same laser also provides a method to sense and correct for temperature changes as small as 85 nanoKelvin, or 85 billionths of a degree.
“Today, ultra-low expansion (ULE) cavity lasers exhibit the narrowest linewidth and highest performance, but they are bulky and very sensitive to environmental noise,” said William Loh, the paper’s first author. “Our goal is to replace ULE lasers with one that could be portable and isn’t sensitive to environmental noise.”
Achieving narrow linewidth
The researchers developed a laser based on a short loop (~2 meters) of optical fiber configured as a ring resonator. Fiber lasers are compact and rugged and tend to react relatively slowly to environmental changes. The researchers combined the advantages of fiber with a nonlinear optical effect known as Brillouin scattering to achieve a laser with a linewidth of just 20 hertz. For comparison, other fiber lasers can achieve linewidths between 1000 to 10,000 hertz, and off-the-shelf semiconductor lasers typically have a linewidth of around 1 million hertz.
To make the laser extremely stable in the face of long- and short-term environmental changes, the researchers developed a way to reference the laser signal against itself to sense temperature changes. Their method is highly sensitive compared to other approaches for measuring temperature and allows the calculation of a precise correction signal that can be used to bring the laser back to the emission wavelength of the original temperature.
“Temperature is an important contributor to laser noise,” said Loh. “A high-quality laser needs to not only have a narrow laser linewidth but also a way to keep that emission stable over the long term.”
This new light source could be used to improve a new generation of optical atomic clocks used for GPS-enabled devices. GPS enables users to pinpoint their location on Earth by triangulating with the signals received from a network of satellites containing advanced atomic clocks. Each satellite provides a time stamp, and the system calculates a location based on the relative differences among those times.
“We think that atomic clocks based on our stable, narrow linewidth laser could be used to more precisely pinpoint the signal’s time of arrival, improving the location accuracy of today’s GPS systems,” said Loh. “The fact that our laser is compact means it could be used aboard satellites.”
The laser could also be beneficial for interferometers like the ones used by the Laser Interferometer Gravitational-wave Observatory (LIGO) to detect gravitational waves coming from colliding black holes or collapsing stars. Ultrastable lasers are necessary for this application because laser noise prevents the interferometer from being able to detect the very small perturbations of a gravitational wave.
“There are efforts underway to use lasers in space to create longer interferometer arms for gravitational wave observation,” said Loh. “Due to its compact size and robustness, our laser might be a candidate for gravitational wave detection in space.”
The researchers say that although their new laser is robust, it is currently a benchtop system suitable for laboratory use. They are now working to develop smaller packaging for the laser and will incorporate smaller optical components to create a portable version that might be as small as a smartphone.
HP shows off new desktop portfolio
HP has unveiled its next-generation HP EliteDesk 800 and ProDesk 600 and 400 series desktop computers. The new portfolio is designed to power flexible workspaces and to take on modern workloads, with 9th Gen Intel Core i9 processors across a broad set of form factors.
Click below to read about the next-gen commercial PCs.
Building on its desktop innovation momentum with the previously announced HP EliteOne 800 G5 All-in-One with optional HP Sure View technology, and the HP EliteDesk 800 G5 Desktop Mini, HP has launched new computers with 9th Gen Intel Core i9 processors.
The portfolio includes HP Sure Sense while harnessing HP’s award-winning security and manageability innovations. HP is also bringing premium features to mainstream form factors to adapt to the changing needs of growing business. A prime example is the addition of touch to the 400 series all-in-ones. HP’s 5th generation Desktop Mini lineup is now updated with optional USB-C with 100W Power Delivery choice. This creates a single cable option for power and video to a display and pairs well with the HP Mini-in-One 23.8-inch Display.
HP provided the following information on its new G5 and G6 series desktop portfolio includes:
- The HP EliteDesk 800 G5 Tower, delivers power, expandability, security, and VR-readiness.
- The HP EliteDesk 800 G5 Small Form Factor, offers big performance in a small footprint, designed for modern workspaces.
- The HP ProDesk 600 G5 Desktop Mini, with single cable connectivity, creates workspaces clean of cords and can be deployed with the HP Mini-in-One or alongside HP EliteDisplay E243d Docking Monitor.
- The HP ProDesk 600 G5 Small Form Factor, features a space-saving design with flexible connectivity.
- The HP ProDesk 600 G5 Micro Tower, offers powerful options and built for expandability.
- The HP ProOne 600 G5 21.5-inch All-in-One, boasts a beautiful, sleek design with a micro-edge display and is built for collaboration while offering versatility and performance.
- The HP ProDesk 400 G6 Small Form Factor, designed to create efficient workspaces with productivity, connectivity, security, and reliability built-in.
- The HP ProDesk 400 G6 Micro Tower, allows users to experience efficiency and power in a mainstream, compact tower, with the latest in performance.
- The HP ProOne 400 G5 20.0-inch and 23.8-inch All-In-One, communication hubs and designed for small businesses and versatile work environments, now with touch displays.
Pricing and Availability: HP Commercial devices will be available in South Africa from July 2019.
Garmin announces USB fast-charger for aircraft
Garmin has launched a small, lightweight USB charger designed for a wide range of aircraft. The GSB 15 contains two USB ports and supports simultaneous 18W (up to 3A) high-speed charging.
Click below to read about the USB fast-charger for aircraft.
The Garmin GSB 15 has received Federal Aviation Administration (FAA) certification, as well as European approval, and is expected to be available next week.
“Tablets and mobile devices have become a mainstay in the cockpit and it’s essential to ensure they’re powered and available throughout an entire flight,” says Carl Wolf, Garmin vice president of aviation sales and marketing. “The GSB 15 is the smallest installed dual-port USB charger ever designed for aircraft use that allows owners and operators to economically add USB power capability to their aircraft.”
Designed specifically for aircraft installations, the device includes two powerful 18W (up to 3A) USB Type-A charging ports that allow pilots and passengers to charge tablets and mobile devices in the cockpit and throughout the cabin in the aircraft. The device is capable of charging two full-size tablets while using them at full backlight. Optional halo lighting around the exterior of the ports allows pilots and passengers to connect to the charger during night time conditions.
Two versions of the GSB 15 are available and allow for installation in space-constrained areas. One version contains a connector on the back of the unit, which is perfect for panel mount installations. A second variant has a connector on the bottom of the device and is suitable for installations in depth-constrained areas, such as near cabin sidewalls. Installation can take the place of an existing aircraft instrument hole with an optional adapter plate. A slim, lightweight design makes it suitable for installation in any cockpit.
Garmin’s aviation business segment is a leading provider of solutions to OEM, aftermarket, military, and government customers. For more information about Garmin’s full line of avionics, go to www.garmin.com/aviation.