title: Reduction of residual amplitude modulation to 1 × 10⁻⁶ for frequency modulation and laser stabilization.
abstract: Active control and cancellation of residual amplitude modulation (RAM) in phase modulation of an optical carrier is one of the key technologies for achieving the ultimate stability of a laser locked to an ultrastable optical cavity. Furthermore, such techniques are versatile tools in various frequency modulation-based spectroscopy applications. In this Letter we report a simple and robust approach to actively stabilize RAM in an optical phase modulation process. We employ a waveguide-based electro-optic modulator (EOM) to provide phase modulation and implement an active servo with both DC electric field and temperature feedback onto the EOM to cancel both the in-phase and quadrature components of the RAM. This technique allows RAM control on the parts-per-million level where RAM-induced frequency instability is comparable to or lower than the fundamental thermal noise limit of the best available optical cavities.
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: M J
authors.initials: MJ
authors.lastname: Martin
authors.forename: C
authors.initials: C
authors.lastname: Benko
authors.forename: J L
authors.initials: JL
authors.lastname: Hall
authors.forename: J
authors.initials: J
authors.lastname: Ye
authors.forename: C
authors.initials: C
authors.lastname: Hagemann
authors.forename: T
authors.initials: T
authors.lastname: Legero
authors.forename: U
authors.initials: U
authors.lastname: Sterr
authors.forename: F
authors.initials: F
authors.lastname: Riehle
authors.forename: G D
authors.initials: GD
authors.lastname: Cole
authors.forename: M
authors.initials: M
authors.lastname: Aspelmeyer