Reaching fiber-laser coherence in integrated photonics

Li, Bohan; Jin, Warren; Wu, Lue; Chang, Lin; Wang, Heming; Shen, Boqiang; Yuan, Zhiquan; Feshali, Avi; Paniccia, Mario; Vahala, Kerry J.; Bowers, John E.

doi:10.1364/ol.439720

Cited by 94 publications

(53 citation statements)

References 21 publications

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“…It is worth mentioning that integrating both III-V and SiN on the same substrate, ensures a robust coupling between the gain and the external cavity regardless of the temperature. Other linewidth narrowing methods, such as hybrid integration with chip-to-chip butt-coupling [22,47], suffer from positional misalignment between different substrates due to thermal expansion mismatch over such a wide temperature range.…”

Section: High-temperature Advantage Of Short-wavelength Picsmentioning

confidence: 99%

Extending the spectrum of fully integrated photonics

Tran¹,

Zhang²,

Morin³

et al. 2021

Preprint

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Integrated photonics has profoundly impacted a wide range of technologies underpinning modern society. The ability to fabricate a complete optical system on a chip offers unrivalled scalability, weight, cost and power efficiency. Over the last decade, the progression from pure III-V materials platforms to silicon photonics has significantly broadened the scope of integrated photonics by combining integrated lasers with the high-volume, advanced fabrication capabilities of the commercial electronics industry. Yet, despite remarkable manufacturing advantages, reliance on silicon-based waveguides currently limits the spectral window available to photonic integrated circuits (PICs). Here, we present a new generation of integrated photonics by directly uniting III-V materials with silicon nitride (SiN) waveguides on Si wafers. Using this technology, we present the first fully integrated PICs at wavelengths shorter than silicon's bandgap, demonstrating essential photonic building blocks including lasers, photodetectors, modulators and passives, all operating at sub-µm wavelengths. Using this platform, we achieve unprecedented coherence and tunability in an integrated laser at short wavelength. Furthermore, by making use of this higher photon energy, we demonstrate superb high temperature performance and, for the first time, kHz-level fundamental linewidths at elevated temperatures. Given the many potential applications at short wavelengths, the success of this integration strategy unlocks a broad range of new integrated photonics applications.

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Section: High-temperature Advantage Of Short-wavelength Picsmentioning

confidence: 99%

Extending the spectrum of fully integrated photonics

Tran¹,

Zhang²,

Morin³

et al. 2021

Preprint

Self Cite

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“…In addition, heterogeneous silicon photonics offers a path towards realizing ultra-stable, high-precision laser performance in a compact and mobile platform and has demonstrated tremendous scalability with 300 mm , which significantly reduces its white frequency noise floor from that of a monolithic III-V DFB [10]. Self-injection locking to a high-Q Si3N4 spiral resonator further suppresses the frequency noise (2), ultimately limited by thermo-refractive noise (TRN) [11,12]. Subsequent PDH locking to a high-finesse, micro-fabricated vacuum cavity [13][14][15] overcomes these limits, drastically reducing the noise down to the cavity thermal noise floor at offsets within the servo bandwidth (3).…”

Section: Introductionmentioning

confidence: 99%

“…Silicon nitride (Si 3 N 4 ) photonics adds even more functionality, taking advantage of CMOS compatibility, wide bandgap, and lowloss integrated waveguides [31][32][33]. Si 3 N 4 -based lasers have especially leveraged low-loss [10,11,[34][35][36] and have demonstrated coherence on par with commercial fiber lasers [12]. However, they are ultimately limited by thermo-refractive noise (TRN), which has kept the fractional frequency instability of planar waveguide and solid dielectric resonators above the 10 −13 level typical of quartz oscillators [37].…”

Section: Introductionmentioning

confidence: 99%

“…For further noise suppression, the E-DBR laser was edge-coupled and self-injection locked to a high-Q Si 3 N 4 spiral resonator on a separate chip [10,12]. In this scheme, resonant backward Rayleigh scattering is fed back to the laser, which drastically suppresses the frequency noise at offset frequencies within the resonance linewidth (1b-2) [49][50][51].…”

Section: Introductionmentioning

confidence: 99%

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Chip-Based Laser with 1 Hertz Integrated Linewidth

Guo¹,

McLemore²,

Xiang³

et al. 2022

Preprint

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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 −14 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 2 /Hz, decreasing to 10 −3 Hz 2 /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 Q of 11.8 billion. Significantly, all the critical components are lithographically defined on planar substrates and hold the potential for parallel high-volume manufacturing, and the total laser system optics can be housed in a 150 mL custom compact module. 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.

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“…The main accessible parameter is the resonator volume, which is physically limited to the size of the semiconductor chip. Recently, 1.41-m long spiral resonators have been demonstrated to suppress thermorefractive noise fluctuations and to dramatically quench laser noise at low offset frequencies [28]. Here, we explore the use of a large mode volume 20.5-mm diameter annulus resonator which exhibits low intrinsic temperature fluctuations.…”

mentioning

confidence: 99%

Cooling of an Integrated Brillouin Laser below the Thermal Limit

Loh,

Kharas,

Maxson

et al. 2021

Preprint

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Photonically integrated resonators are promising as a platform for enabling ultranarrow linewidth lasers in a compact form factor. Owing to their small size, these integrated resonators suffer from thermal noise that limits the frequency stability of the optical mode to ∼100 kHz. Here, we demonstrate an integrated stimulated Brillouin scattering (SBS) laser based on a large modevolume annulus resonator that realizes an ultranarrow thermal-noise-limited linewidth of 270 Hz.In practice, yet narrower linewidths are required before integrated lasers can be truly useful for applications such as optical atomic clocks, quantum computing, gravitational wave detection, and precision spectroscopy. To this end, we employ a thermorefractive noise suppression technique utilizing an auxiliary laser to reduce our SBS laser linewidth to 70 Hz. This demonstration showcases the possibility of stabilizing the thermal motion of even the narrowest linewidth chip lasers to below 100 Hz, thereby opening the door to making integrated microresonators practical for the most demanding future scientific endeavors.

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Reaching fiber-laser coherence in integrated photonics

Cited by 94 publications

References 21 publications

Extending the spectrum of fully integrated photonics

Extending the spectrum of fully integrated photonics

Chip-Based Laser with 1 Hertz Integrated Linewidth

Cooling of an Integrated Brillouin Laser below the Thermal Limit

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