New Fields of investigation

BUILDING ON OUR RICH HERITAGE IN LASERS AND OPTICS, today’s HRL researchers are using their in-depth knowledge to bring speed, power and agility to the vision, sensing and targeting systems of tomorrow. HRL has demonstrated expertise in laser sources, volume Bragg gratings, modulators, beam steering, fibers, wavelength-division multiplexing (WDM), detectors, atmospheric effects, propagation modeling, architectures for laser communications including retro-modulators, and hybrid mm-wave/optical sources. We are applying our strength in the development of unique lasers, both fiber and solid state, to produce new milestones in power, pulse format and flexibility. Currently we are enabling new technology solutions for our LLC Member companies and the government through our work on long range detection of chemicals, and the development of low-cost sources for imaging sensors in the terahertz region of the spectrum.

NOVEL FIBER LASERS

Recently, the HRL laser team has developed many types of specialized fiber lasers and amplifiers that can generate very flexible optical pulse formats from continuous operation, to high repetition rate (1 kHz – 1 MHz), to mode-locked laser sources that were not possible before. We have built fiber lasers with record coherence and power output. These new optical sources can be an important enabler for future imaging, radar, illumination and detecting systems.

COHERENT COMBINING OF LASERS

HRL is exploiting new physics to conceive, design and demonstrate the coherent combining of individual lasers to achieve unparalleled robustness, light intensity and power output. Individual fiber and diode lasers are efficient (30 and 70%, respectively) and flexible, with minimal thermal problems compared to other solid state lasers. Our approach “coherently combines” these individual elements using “self-organizing” principles. The result, which we have demonstrated with a large number of fiber lasers, is a simple and robust system where active control of the individual elements is unnecessary.

HRL has also invented and demonstrated a simple method to phase up arrays of fiber amplifiers, while retaining the energy efficiency, opto-mechanical robustness, and form flexibility of fibers.We applied this fiber amplifier phasing to free space laser communication to build a power scalable transmitter that can mitigate the atmospheric turbulance and thus increase the signal reaching the receiver by approximately 10 dB, as we demonstrated in our outdoor laser communication test range. This phasing approach can also be used with multiple coherent receive apertures to increase the signal.

In a successful technology transition story, the light amplifying ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser materials and the precise beam replicating phase conjugation technologies we have developed in the past are now forming the basis of the design for the next-generation of high-power lasers for directed energy weapons.

developing technologies