12 research outputs found
Hertz-linewidth semiconductor lasers using CMOS-ready ultra-high- microresonators
Driven by narrow-linewidth bench-top lasers, coherent optical systems
spanning optical communications, metrology and sensing provide unrivalled
performance. To transfer these capabilities from the laboratory to the real
world, a key missing ingredient is a mass-produced integrated laser with
superior coherence. Here, we bridge conventional semiconductor lasers and
coherent optical systems using CMOS-foundry-fabricated microresonators with
record high factor over 260 million and finesse over 42,000. Five
orders-of-magnitude noise reduction in the pump laser is demonstrated, and for
the first time, fundamental noise below 1 Hz Hz is achieved in an
electrically-pumped integrated laser. Moreover, the same configuration is shown
to relieve dispersion requirements for microcomb generation that have
handicapped certain nonlinear platforms. The simultaneous realization of
record-high factor, highly coherent lasers and frequency combs using
foundry-based technologies paves the way for volume manufacturing of a wide
range of coherent optical systems.Comment: 19 pages, 11 figure
Chip-Based Laser with 1 Hertz Integrated Linewidth
Lasers with hertz-level linewidths on timescales up to seconds are critical
for precision metrology, timekeeping, and manipulation of quantum systems. Such
frequency stability typically relies on bulk-optic lasers and reference
cavities, where increased size is leveraged to improve noise performance, but
with the trade-off of cost, hand assembly, and limited application
environments. On the other hand, planar waveguide lasers and cavities exploit
the benefits of CMOS scalability but are fundamentally limited from achieving
hertz-level linewidths at longer times by stochastic noise and thermal
sensitivity inherent to the waveguide medium. These physical limits have
inhibited the development of compact laser systems with frequency noise
required for portable optical clocks that have performance well beyond
conventional microwave counterparts. In this work, we break this paradigm to
demonstrate a compact, high-coherence laser system at 1548 nm with a 1 s
integrated linewidth of 1.1 Hz and fractional frequency instability less than
10 from 1 ms to 1 s. The frequency noise at 1 Hz offset is suppressed
by 11 orders of magnitude from that of the free-running diode laser down to the
cavity thermal noise limit near 1 Hz/Hz, decreasing to 10 Hz/Hz
at 4 kHz offset. This low noise performance leverages wafer-scale integrated
lasers together with an 8 mL vacuum-gap cavity that employs micro-fabricated
mirrors with sub-angstrom roughness to yield an optical of 11.8 billion.
Significantly, all the critical components are lithographically defined on
planar substrates and hold the potential for parallel high-volume
manufacturing. Consequently, this work provides an important advance towards
compact lasers with hertz-level linewidths for applications such as portable
optical clocks, low-noise RF photonic oscillators, and related communication
and navigation systems
Integrated AlGaInAs-silicon evanescent race track laser and photodetector
Recently, AlGaInAs-silicon evanescent lasers have been demonstrated as a method of integrating active photonic devices on a silicon based platform. This hybrid waveguide architecture consists of III-V quantum wells bonded to silicon waveguides. The self aligned optical mode leads to a bonding process that is manufacturable in high volumes. Here give an overview of a racetrack resonator laser integrated with two photo-detectors on the hybrid AlGaInAs-silicon evanescent device platform. Unlike previous demonstrations of hybrid AlGaInAs-silicon evanescent lasers, we demonstrate an on-chip racetrack resonator laser that does not rely on facet polishing and dicing in order to define the laser cavity. The laser runs continuous-wave (c.w.) at 1590 nm with a threshold of 175 mA, has a maximum total output power of 29 mW and a maximum operating temperature of 60 C. The output of this laser light is directly coupled into a pair of on chip hybrid AlGaInAs-silicon evanescent photodetectors used to measure the laser output
High-performance lasers for fully integrated silicon nitride photonics.
Silicon nitride (SiN) waveguides with ultra-low optical loss enable integrated photonic applications including low noise, narrow linewidth lasers, chip-scale nonlinear photonics, and microwave photonics. Lasers are key components to SiN photonic integrated circuits (PICs), but are difficult to fully integrate with low-index SiN waveguides due to their large mismatch with the high-index III-V gain materials. The recent demonstration of multilayer heterogeneous integration provides a practical solution and enabled the first-generation of lasers fully integrated with SiN waveguides. However, a laser with high device yield and high output power at telecommunication wavelengths, where photonics applications are clustered, is still missing, hindered by large mode transition loss, non-optimized cavity design, and a complicated fabrication process. Here, we report high-performance lasers on SiN with tens of milliwatts output power through the SiN waveguide and sub-kHz fundamental linewidth, addressing all the aforementioned issues. We also show Hertz-level fundamental linewidth lasers are achievable with the developed integration techniques. These lasers, together with high-Q SiN resonators, mark a milestone towards a fully integrated low-noise silicon nitride photonics platform. This laser should find potential applications in LIDAR, microwave photonics and coherent optical communications
Issues associated with polarization independence in silicon photonics
Interest in silicon photonics is experiencing a dramatic increase due to emerging applications areas and several high profile successes in device and technology development. Despite early work dating back to the mid-1980s, dramatic progress has been made only in the recent years. While many approaches to research have been developed, the striking difference between the work of the early to mid-1990s, and more recent work, is that the latter has been associated with a trend to reduce the cross sectional dimensions of the waveguides that form the devices. The question arises therefore, as to whether one should move to very small strip waveguides (silicon wires) of the order of 250 nm in height and a few hundred nanometres in width for improved device performance but with little hope of polarization independence, or to utilize slightly larger rib waveguides that offer more opportunity to control the polarization dependence of the devices. In this paper, we discuss the devices suitable for one approach or the other, and present the designs associated both with strip and rib waveguides. In particular, we present the designs of polarization-independent ring resonators with free spectral ranges up to 12 nm, we propose modulators for bandwidths in the tens of gigahertz regime, and present grating-based couplers for rib and strip waveguides, and/or for wafer scale testing, as well as a novel means of developing Bragg gratings via ion implantation
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Chip-based laser with 1-hertz integrated linewidth
Lasers with hertz linewidths at time scales of seconds are critical for metrology, timekeeping, and manipulation of quantum systems. Such frequency stability relies on bulk-optic lasers and reference cavities, where increased size is leveraged to reduce noise but with the trade-off of cost, hand assembly, and limited applications. Alternatively, planar waveguide-based lasers enjoy complementary metal-oxide semiconductor scalability yet are fundamentally limited from achieving hertz linewidths by stochastic noise and thermal sensitivity. In this work, we demonstrate a laser system with a 1-s linewidth of 1.1 Hz and fractional frequency instability below 10-14 to 1 s. This low-noise performance leverages integrated lasers together with an 8-ml vacuum-gap cavity using microfabricated mirrors. All critical components are lithographically defined on planar substrates, holding potential for high-volume manufacturing. Consequently, this work provides an important advance toward compact lasers with hertz linewidths for portable optical clocks, radio frequency photonic oscillators, and related communication and navigation systems