This paper describes the technology development of the master oscillator (MO) as part of the NASA laser transmitter for the LISA mission. The MO is based on the non-planar ring oscillator (NPRO) resonator design.
NASA Goddard Space Flight Center (GSFC) is developing a master oscillator power amplifier (MOPA) laser transmitter for the Laser Interferometer Space Antenna (LISA) mission. The laser transmitter is one of the potential contributions to the LISA mission from NASA. Our development effort has included a master oscillator (MO), a power amplifier (PA), a frequency reference system (FRS), a power monitor detector (PMON), and laser electronics module (LEM). We are working on their design, performance evaluation, environmental testing, and reliability testing for space flight. We have built TRL 4 laser optical modules based on the MO and PA, which meets most performance requirements. One of the TRL 4 laser optical modules has been delivered to ESA for independent evaluation. TRL 6 versions of MO and PA are being built and evaluated at GSFC. TRL 5 and 6 versions of laser electronics are under development. In this paper, we will describe our progress to date and plans to demonstrate and deliver a TRL 6 laser demonstrator system to ESA by 2024.
We present the status of ongoing work at NASA-Goddard Space Flight Center (GSFC) to build a low-cost flexible ground terminal for optical communication. Previous laser communication missions at NASA have been supported by one-of-akind ground terminals built specifically for each mission. If NASA is to build a global network of optical terminals to enable widespread use of optical communications, then a blueprint for an economical ground terminal able to support a variety of missions is needed. With this goal in mind, NASA is constructing a ground terminal in Greenbelt, Maryland to enable testing of new ground terminal technologies from industry to academia.
NASA Goddard Space Flight Center is developing a master oscillator power amplifier (MOPA) laser transmitter for the ESA-led Laser Interferometer Space Antenna (LISA) mission. Taking advantage of our space laser experience and the emerging telecom laser technology, we are developing a full laser system for the LISA mission. Our research effort has included both master oscillator (MO) and power amplifier (PA) developments, and their environmental testing and reliability for space flight. Our current baseline for the MO is a low-mass, compact micro non-planar ring oscillator (m- NPRO) laser. The amplifier uses a robust mechanical design based on fiber components. We have performed laser system noise tests by amplitude- and frequency-stabilizing the PA output. We will describe our progress and plans to demonstrate a TRL 6 laser system, which is an essential step toward qualifying lasers for space applications, by 2021.
A highly stable and long-lifetime laser system is a key component of the space-based Laser Interferometer Space Antenna (LISA) mission, which is designed to detect gravitational waves from various astronomical sources. We are developing such laser system at the NASA Goddard Space Flight Center (GSFC). Our baseline architecture for the LISA laser consists of a low-power, low-noise small Nd:YAG non-planar ring oscillator (micro NPRO) followed by a diodepumped Yb-fiber amplifier with ~2 W output. In this paper, we will describe our progress to date and plans to demonstrate a technology readiness level (TRL) 6 LISA laser system.
Fiber amplifiers have been used in many laser communication applications due to their compactness and high efficiency. However, fiber amplifiers for free space laser communications have been limited to low peak power communication formats due to nonlinear effects such as Self Phase Modulation (SPM). At high peak powers, SPM can broaden the spectrum of free space laser communication signals to an unacceptable degree, moving much of the transmitted power outside the receiver’s designed bandwidth. The Laser Communication Relay Demonstration (LCRD) needed a fiber amplifier that could amplify a 3.5 GHz wide signal to peak powers of nearly a kilo-Watt with little to no spectral broadening due to SPM. We tested several different commercial amplifiers and found an Er-doped, Very Large Mode Area (VLMA) fiber amplifier, pumped by a 1480 nm Raman fiber laser, met the needs for both high peak power and minimal spectral broadening. The high peak power performance of the VLMA amplifier is enabled by the large effective area of ~ 1100 μm2 . We will present a detailed analysis of the effects of SPM on the amplified signal spectrum for both pulse position modulation (PPM) and differential phase shift keyed (DPSK) communication formats at peak powers up to 1 kW. Additionally, Bit Error Ratio (BER) performance data taken with the LCRD modem showed the signal did not suffer a measureable penalty from amplification with the VLMA amplifier. The ability to reach the required high peak power with this fiber amplifier makes it possible to consider its use for deep space laser communication, e.g. with high order M-ary PPM formats where such high peak powers are needed.
High gain Erbium Doped Fiber Amplifiers (EDFAs), while revolutionizing optical communications, remain vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that, due to spontaneous Q switching, produce random pulses with high peak power, i.e. giant pulses. Giant pulses can damage either the components within a high gain EDFA or the external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on conditions under which normal pulses evolve into giant pulses, and provide results on the transient effects of giant pulses on an amplifier’s fused-fiber couplers, such as pump-signal combining wavelength division multiplexers (WDMs), an effect which we call Fused-coupler Overload Induced Leakage (FOIL). While FOIL’s effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent, e.g. damage to the pump’s front facet.
communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (>50%) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their space communication and ranging performances using both the 2 detected photon threshold and coincidence methods.
We present performance data for novel photon-counting detectors for free space optical communication. NASA GSFC is testing the performance of three types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We present and compare dark count, photon-detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance.
The HgCdTe APD array routinely demonstrated photon detection efficiencies of greater than 50% across 5 arrays, with one array reaching a maximum PDE of 70%. We performed high-resolution pixel-surface spot scans and measured the junction diameters of its diodes. We found that decreasing the junction diameter from 31 μm to 25 μm doubled the e- APD gain from 470 for an array produced in the year 2010 to a gain of 1100 on an array delivered to NASA GSFC recently. The mean single-photon SNR was over 12 and the excess noise factors measurements were 1.2-1.3.
The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output.
A free space optical communication link with simulated atmospheric turbulence investigation using un-cooled Mid-Wave Infrared (MWIR) system. Uncooled pulsed Quantum Cascade Laser was used as transmitter and photoelectromagnetic detector as receiver. For high photon efficiency and to eliminate QCL thermal effects signal was modulated at 32-ary Pulse Position Modulation (PPM) scheme. Concept enables extremely small and atmospheric propagation efficient optical communication system.
KEYWORDS: Fiber Bragg gratings, Thermal modeling, Autoregressive models, Temperature metrology, Data modeling, System identification, Systems modeling, Control systems, Optoelectronic devices, Performance modeling
NASA GSFC’s Thermal Signature Identification System (TheSIS) 1) measures the high order dynamic responses of
optoelectronic components to direct sequence spread-spectrum temperature cycling, 2) estimates the parameters of
multiple autoregressive moving average (ARMA) or other models the of the responses, 3) and selects the most
appropriate model using the Akaike Information Criterion (AIC). Using the AIC-tested model and parameter vectors
from TheSIS, one can 1) select high-performing components on a multivariate basis, i.e., with multivariate Figures of
Merit (FOMs), 2) detect subtle reversible shifts in performance, and 3) investigate irreversible changes in component or
subsystem performance, e.g. aging. We show examples of the TheSIS methodology for passive and active components
and systems, e.g. fiber Bragg gratings (FBGs) and DFB lasers with coupled temperature control loops, respectively.
A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a
single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic
lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed
cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors
serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors
also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting
in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved
pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state
lasers.
The LCRD will demonstrate optical communications relay services between a geosynchronous satellite and Earth over
an extended period, and thereby gain the knowledge and experience base that will enable NASA to design, procure, and
operate cost-effective future optical communications systems and relay networks. LCRD is the next step in NASA
eventually providing an optical communications service on the Next Generation Tracking and Data Relay Satellites
(TDRS). LCRD will demonstrate some optical communications technologies, concepts of operations, and advanced
networking technologies applicable to Deep Space missions. In this paper we describe the integrated dual format
(PPM/DPSK) modem testbed development and performance.
We report on half-Watt level single spatial mode superluminescent laser diode at 1335 nm. Output optical power in excess of 500 mW from a single facet of angle-striped waveguide was realized at 10°C of heatsink temperature with peak electro-optical efficiency of 28%. To our knowledge this is the highest optical power and electro-optic conversion efficiency in a SLED device reported so far in the literature. Further optimization could lead to revolutionary result: 1) the creation of a high power optical device (SLED) with electro-optical efficiencies approaching and/or exceeding that of Fabry-Perot lasers (counting both facet outputs) with absolute optical power levels compared to that of Fabry-Perot lasers, 2) Electro-optical efficiencies approaching internal quantum efficiencies which could well exceed the 70-80% range observed in present commercial semiconductor laser and light-emitting structures.
This paper describes the development and testing of a 4 channel, 10 Gbps/channel WDM module. This model incorporates four DFB lasers whose wavelengths are spaced 1.6 nm apart within the 1550 nm fiber window. A driver circuit have been developed based on a commercially-available monolithic amplifier which provides high-speed operation at low cost. The performance of the module was measured at 10 Gbps and 2.5 Gbps. Time-domain performance and crosstalk results are presented.
Intrinsically large mode semiconductor lasers and mode transformers monolithically integrated with semiconductor lasers, are two promising approaches for making alignment tolerant structures that can be used for passive alignment to single mode optical fibers. This technique, in conjunction with a recently developed silicon waferboard integration scheme, will significantly simplify the assembly process and the packaging of transmitter laser arrays. The passive alignment technique consists of octagonal electrodeposited copper bosses to physically register the laser chip with percussion etched inverted pyramidal receptacles and v-grooves in a silicon substrate.
Mario Dagenais, Si Cho, Ping-Hui Yeh, Stephen Fox, R. Prakasam, Peter Heim, Scott Merritt, C.-C. Lu, Vijayanand Vusirikala, Badri Gopalan, Suryaprasad Kareenahalli, Colin Wood
KEYWORDS: Optical amplifiers, Laser amplifiers, Semiconductor lasers, High power lasers, Semiconductors, High power fiber amplifiers, Near field optics, Semiconductor optical amplifiers, Near field, Gaussian beams
A normal incidence tapered laser amplifier is shown to produce more than 4.5 W optical power at 810 nm in a diffraction-limited beam. A new angled-facet tapered laser amplifier has demonstrated as much as 5 W optical power in a diffraction-limited beam at 810 nm with only a few mWs of coupled input power. Angled-facet laser amplifiers exhibit near-ideal Gaussian beam characteristics. More than 1.9 W CW is obtained in a 970 nm angled-facet tapered laser amplifier. A near-ideal beam quality factor M2 is obtained.
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