Watt-class semiconductor optical amplifiers (SOAs) at 1550nm are an attractive alternative to replace erbium-doped fiber amplifiers (EDFAs) in various applications including free space optical communications (FSO), with the potential to be more efficient, compact, and cost-effective while providing high-power diffraction-limited output. We present a single mode fiber-coupled packaged SOA delivering >30dBm (1.2W) of continuous wave ex-fiber power at 1550nm with 16dB of overall gain, enabled by recent advancements in diffraction-limited output from tapered semiconductor amplifiers. Preliminary data communications measurements are presented, with an open eye diagram achieved with >1W of output power at 10Gbps using the differential phase shift keying (DPSK) communications format. Watt-class collimated and fiber-coupled SOAs are available and being shipped to customers now.
Applications such as LIDAR, ranging/ sensing, and optical communications all require photonic components, such as sources, detectors, and modulators, to be integrated into a single system. For spaceborne applications, SWaP (size, weight and power) is a key consideration: a monolithic indium phosphide (InP) Photonic Integrated Circuit (PIC) can integrate many components onto a chip with a footprint of a few square mm. Photonic Wirebonding (PWB) enables seamless integration of best-in-class optical devices from disparate materials. Connecting and mode-matching different photonic components enables versatility and functionality unachievable by other methods, facilitating co-packaging. PICs and PWBs do not yet have spaceflight heritage: demonstrating increased Technology Readiness Level (TRL) is a key step toward use in orbital and spaceborne missions. Freedom Photonics presents our first hermetic photonic wirebonded PIC package, alongside recent environmental testing results demonstrating that our PIC and PWB technologies are suitable for the harsh conditions of launch and spaceflight: shock, vibration, radiation, and temperature cycling.
Tunable and ultra-narrow linewidth lasers that are fully integrated remain a missing component and challenge for the thin-film lithium niobate platform, while being useful for applications ranging from data communication to signal processing. Here, we present, for the first time, the demonstration of fully integrated, extended cavity diode lasers combining C-band semiconductor gain chips with TFLN using photonic wire bonding. By leveraging the scalability of photonic wirebonding the laser, with two intra-cavity RSOAs, produces a high on-chip output power of 35 mW and shows single frequency operation with more than 61 dB side mode suppression. By adjusting on-chip heaters the laser can be tuned over >40 nm across the entire gain bandwidth. Using delayed self-heterodyne detection an ultra-narrow, intrinsic linewidth of 1.4 kHz is measured.
High brightness semiconductor diode lasers can provide tremendous system-level advantages for many applications. Recent advancements in InP-based edge-emitting diode lasers operating in the 1500 – 1600 nm wavelength band could enable compact, direct diode solutions with performance metrics that previously could only be met by fiber-based lasers or solid-state laser systems. We report on high power, high beam quality diode lasers at 1550 nm based on a tapered chip architecture. We have demonstrated ⪆5 W of continuous wave output power at room temperature, with a slow axis beam propagation factor M2 of 1.1, corresponding to a slow axis linear brightness of 9.2 W mm-1 mrad-1. We have also demonstrated a fully packaged watt-class single mode fiber-coupled Semiconductor Optical Amplifier (SOA) based on this technology. This package delivers ⪆30 dBm (1.2 W) ex-fiber saturation output power, ten times higher saturation power than the prior state-of-the-art. This result is achieved with an input seed power of 30 mW (approximately 15 dBm), corresponding to an overall gain of approximately 16 dB. To demonstrate the functionality of the SOA, we have carried out linewidth measurements and data transmission measurements. These tapered lasers and amplifiers offer great potential benefit for many pumping and direct use applications.
Watt-class semiconductor optical amplifiers (SOAs) at 1550 nm are an attractive alternative to replace erbium-doped fiber amplifiers (EDFAs) in various applications including remote sensing, optical communications, illumination, and LIDAR, with the potential to be more efficient, compact, and cost-effective. We report a world record of a single mode fiber-coupled packaged semiconductor optical amplifier delivering >30 dBm (1.2 W) of continuous wave ex-fiber power at 1550 nm, enabled by recent advancements in diffraction-limited output from tapered diode laser amplifiers. This result is achieved with an input seed power of 30 mW (~15 dBm), corresponding to an overall gain of ~16 dB. Reliability data will be presented for our tapered laser chips, as will progress towards demonstration of high performance SOAs in an optical link. Watt-class SOAs are available and being shipped to customers now.
Photonic wire bonding is a disruptive technology that solves the problem of efficiently coupling light between best-inbreed integrated photonic chips, providing insertion losses unattainable with other hybrid integration techniques. Enabled by advances in machine vision technology, photonic wire bonding uses two-photon polymerization to print a waveguide with arbitrary 3D geometry for connecting dissimilar integrated waveguides. Unlike butt-coupling hybrid integration approaches, specialized waveguide edge couplers and precise alignment between chips are not required since the photonic wire bond (PWB) is customized to a given pair of waveguides. The machine vision system detects the onchip waveguide facet locations and orientations for accurate placement of the PWB. Mode converters in the PWB efficiently transition light between the dissimilar optical spatial modes. Other hybrid integration approaches, including butt-coupling, flip-chip bonding, direct wafer bonding, and heteroepitaxy cannot achieve comparable insertion losses and are limited in their applicability and throughput. Freedom Photonics (a Luminar company) has demonstrated worldclass coupling losses between best-in-breed photonic platforms using a photonic wire bonding tool from Vanguard Automation. In this paper, we present photonic wire bond results between high performance semiconductor lasers and silicon nitride and lithium niobate waveguides as well as opportunities for prototyping of next generation, highly integrated photonic sub-assemblies.
Watt-class semiconductor optical amplifiers (SOAs) at 1550 nm are an attractive alternative to replace erbium-doped fiber amplifiers (EDFAs) in various applications including remote sensing, optical communications, and LIDAR, with the potential to be more efficient, compact, and cost-effective. We report a world record of a single mode fiber-coupled packaged semiconductor optical amplifier delivering >30 dBm (1.2 W) of continuous wave ex-fiber power at 1550 nm, enabled by recent advancements in diffraction-limited output from tapered diode laser amplifiers. This result is achieved with an input seed power of 30 mW (~15 dBm), corresponding to an overall gain of ~16 dB, and the noise figure is calculated to be 5.4 dB. We have begun reliability testing of our tapered laser chips, and we are investing in the productization of these packaged watt-class SOAs.
Atmospheric methane trends over the last few years have been increasing at a rate of 7-12 parts per billion (ppb) per year after brief a pause in the first decade of this century. The reasons for the pause and subsequent increase remains unclear. Thus, there is a critical need for additional, precise and accurate methane observations to understand the natural and anthropogenic processes that drive the trends in atmospheric methane and to constrain its sources, and sinks. At NASA Goddard Space Flight Center (GSFC), in collaboration with Freedom Photonics Inc., we have been developing a lidar to measure atmospheric methane using Integrated Path Differential Absorption (IPDA) from an airborne platform as a precursor to a future space mission. In this paper we present the design of a laser transmitter operating at ~1651 nm based on a newly developed Distributed Bragg Grating (DBR) seed laser and an Optical parametric oscillator (OPO). The DBR is rapidly step-tuned over the methane absorption at several discrete wavelengths. This multi-wavelength approach enables us to sample the entire methane lineshape and reduce systematic errors.
Freedom Photonics and the University of Virginia have developed high power, wide-bandwidth balanced photodetectors based on vertically-illuminated modified uni-traveling carrier (MUTC) photodiode technology. These balanced pairs are based on single photodiodes which achieve 3-dB bandwidths of 25 GHz, coupled with output powers above 23 dBm, as well as 35 GHz photodiodes with output powers greater than 19 dBm. A balanced configuration of these devices offers advantages in common-mode noise reduction, increasing the signal-to-noise ratio. In a photonic link, high-power, balanced photodiodes support high link gain and large bandwidths, while the high linearity of these devices maximizes spurious-free dynamic range (SFDR).
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