Small Business Innovation Research/Small Business Tech Transfer
High Average Power Fiber Laser for Satellite Communications
Project Description
Very high average power lasers with high electrical-top-optical (E-O) efficiency, which also support pulse position modulation (PPM) formats in the MHz-data rate speeds, do not currently exist. Solid-state lasers fail to provide the necessary E-O requirements due to low quantum efficiency and excess heat generation. MHz-speed modulation formats are not supported by fiber lasers at very high average powers due to nonlinearities. These nonlinearities cause instabilities in the output power, and also cause the optical spectrum to exceed the system requirements. A very high power, short pulse fiber laser is proposed which can operate in two modes of operation; a targeting/beacon mode, and a data transmit mode. The very high average powers are achieved by filling the time-slot of a PPM format scheme with a high-duty-cycle sequence of much shorter pulses. This allows the nonlinearities in the fiber laser to be mitigated and allow very high average powers within the required bandwidth spectrum. A seed laser which emits picosecond pulses will be driven by electronics to provide a very high duty cycle modulated by a slower modulation envelope to allow for PPM data transmission. The very high duty cycle will allow the average power to increase while keeping the peak powers low through a series of Yb-doped fiber amplifiers. A factor of two is targeted between the peak and average powers. The fiber amplifiers will used highly doped Yb-doped fibers in order to keep the fiber lengths to a minimum, which minimizes nonlinear effects such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and self-phase modulation (SPM). The modulation format to support the targeting/beacon mode will be accomplished by turning the final fiber amplifier(s) on/off. This is possible due to the upper state lifetime of the Yb ions in the fiber amplifiers.
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Anticipated Benefits
The Jet Propulsion Lab (NASA JPL) facility is pursuing technology to enable a long range optical telecommunication system involving a communications laser, telescope, satellite, and receiver. A very high average power, PPM format communications laser can be used to form a high speed data link with satellites orbiting the Earth and potentially to satellites or stationary targets on other celestial bodies. Long range optical telecommunication systems based on optical technology can help negate the expense of large, cumbersome transmitter and receiver systems based on other technologies, such as radio frequencies, due to the diffraction properties of the transmitted frequency.
Laser-based manufacturing and the directed energy communities can benefit from kW-class, pulsed fiber laser technology. Precise drilling and cutting of various materials with ns-pulse lasers is currently a reality for up to 100 Watts of output. The increased average powers and shorter pulses offered by this technology can increase throughput for laser-based manufacturing, and/or allow thicker materials to be more precisely cut and drilled. The directed energy community has been engaged in high average power laser technology for several years now. These sources are currently operated in continuous wave (CW) mode with a narrow bandwidth in order to combine multiple sources to further increase the average powers. High average power, pulsed laser technology, especially with an arbitrary waveform format, may offer distinct advantages for not only depositing energy on the target, but aid in sensor-defeat methods as well. More »
Laser-based manufacturing and the directed energy communities can benefit from kW-class, pulsed fiber laser technology. Precise drilling and cutting of various materials with ns-pulse lasers is currently a reality for up to 100 Watts of output. The increased average powers and shorter pulses offered by this technology can increase throughput for laser-based manufacturing, and/or allow thicker materials to be more precisely cut and drilled. The directed energy community has been engaged in high average power laser technology for several years now. These sources are currently operated in continuous wave (CW) mode with a narrow bandwidth in order to combine multiple sources to further increase the average powers. High average power, pulsed laser technology, especially with an arbitrary waveform format, may offer distinct advantages for not only depositing energy on the target, but aid in sensor-defeat methods as well. More »
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Primary U.S. Work Locations and Key Partners
| Organizations Performing Work | Role | Type | Location |
|---|---|---|---|
| Q-Peak, Inc. | Lead Organization | Industry | Bedford, Massachusetts |
| Jet Propulsion Laboratory (JPL) | Supporting Organization | FFRDC/UARC | Pasadena, California |
Primary U.S. Work Locations
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California
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Massachusetts
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