Sub-hertz relative frequency stabilization of two-diode laser-pumped Nd:YAG lasers locked to a Fabry-Perot interferometer

Abstract

Abstrucr-Two-diode laser-pumped Nd : YAG lasers have been frequency stabilized to a commercial 6.327 GHz free spectral range Fabry-Perot interferometer yielding a best-case beatnote linewidth of 330 mHz. In addition, a Fabry-Perot interferometer with a free spectral range of 680 MHz, a linewidth of 25 kHz, and a finesse of 27 500 has been built and when it was substituted in place of the commercial interferometer produced a robust and easily repeatable beatnote linewidth of 700 mHz.

Demonstration of a passive subpicostrain fiber strain sensor

“…By detecting and demodulating the beam reflected off the Fabry-Perot cavity, a high signal-to-noise error signal is derived, yielding the instantaneous frequency difference between the laser frequency and the cavity resonance [7], [8]. This scheme has found many applications in areas involving laser stabilization and signal extraction [9], [10]. The most demanding application of the PDH technique is in the detection schemes for gravitational waves, which require strain sensitivities approaching ∆L/L = 10…”

“…We present a fiber sensing system with, to our knowledge, an unprecedented strain sensitivity of better than 10 −12 ε/ √ Hz, in a band extending down to 100 Hz. The power of the PDH technique lies in its shot noise limited closed-loop spectral density of frequency noise, which is given by [9] S f,clmin (Hz/ √ Hz) = ∆ν c J 0 (β) …”

“…We present a fiber sensing system with, to our knowledge, an unprecedented strain sensitivity of better than 10 −12 ε/ √ Hz, in a band extending down to 100 Hz. The power of the PDH technique lies in its shot noise limited closed-loop spectral density of frequency noise, which is given by [9] S f,clmin (Hz/ √ Hz) = ∆ν c J 0 (β) where ∆ν c is the full-width half-maximum (FWHM) linewidth of the FFP resonance; β is the modulation depth; ν is the optical frequency of the laser carrier; η is the photodectector quantum efficiency; and P i is the input interrogating optical power. Eqn.…”

Phase-sensitive interrogation of fiber Bragg grating resonators for sensing applications

“…Towards achieving this ultra resolution, the Pound-Drever-Hall (PDH) laser frequency locking scheme [19]- [21] is widely used. It is adopted for laser frequency stabilization [22], [23], interferometer longitudinal control, as well as gravitational wave signal extraction [24]- [27]. While the PDH frequency locking technique is wellestablished with free-space bulk-optical resonators and solidstate lasers within the gravitational wave community, it can readily be extended to diode laser stabilization [28], and guided-wave optics.…”

Refractometry with Ultralow Detection Limit Using Anisotropic Whispering-Gallery-Mode Resonators

“…The detection limit of this approach is determined by two key factors: the coupling strength of the target into the resonant mode and the minimum detectable change in mode frequency. This minimum-detectable-frequency change is usually set for passive detection schemes by photon shot noise in the frequency locking system [7][8][9], or by thermomechanical or thermorefractive noise in the resonator [10,11]. Active detection schemes have limits set through Schawlow-Townes processes [12,13].…”