Measurement of the Coherence Limits of Narrow-Linewidth Si/III-V Lasers
Abstract
Narrow-linewidth lasers play an important and increasing role in a wide variety of applica-tions, from sensing and spectroscopy to optical communication and on-chip clocks. Semiconduc-tor lasers are dominant in many fields due to their advantage in size, cost, and power consump-tion. Nevertheless, their linewidth is historically limited to the sub-MHz regime, and therefore are rarely used for high-coherence applications. It has been recently demonstrated that a new design paradigm, in which the optical energy is stored away from the active region in a composite high-Q resonator, has the potential to dramatically improve the coherence of the laser. A ground-breaking experimental result of sub-KHz noise-floor was demonstrated by implementing this approach on the hybrid Si/III-V platform. However, an exact equivalent linewidth value could not be measured due to technical noise induced by the measurement setup. Specifically, insufficient output power mandated the use of an external amplifier that degraded the coherence properties of the amplified beam. In this proposal we request support for research instrumentation that will allow us to mea-sure the quantum-limited noise-floor of these devices. The instrumentation will interface and upgrade our current frequency noise measurement setup, whereas funds are requested for three main components: low-noise balanced photodetector for a non-amplified measurement, a cryo-genic probe-station to suppress technical noise within the measurement bandwidth, and a fast high-saturation-power balanced photodetector for broadband measurement at room temperature. We show theoretically that these upgrades will improve our noise-floor limit by at least an order of magnitude compared to the current setup. The first generation of high coherence Si/III-V lasers already demonstrated a record upper-bound noise-floor estimate of a KHz. The requested research instrumentation could result in the demonstration of semiconductor lasers with unprecedented, game-changing noise performance, and will support on-going research of newer generations of narrow-linewidth semiconductor lasers.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 04, 2019
- Source ID
- W911NF1510553
Entities
People
- Amnon Yariv
Organizations
- Army Contracting Command
- California Institute of Technology
- United States Army