title: Metrological characterization of custom-designed 894.6 nm VCSELs for miniature atomic clocks.
abstract: We report on the characterization and validation of custom-designed 894.6 nm vertical-cavity surface-emitting lasers (VCSELs), for use in miniature Cs atomic clocks based on coherent population trapping (CPT). The laser relative intensity noise (RIN) is measured to be 1 × 10(-11) Hz(-1) at 10 Hz Fourier frequency, for a laser power of 700 μW. The VCSEL frequency noise is 10(13) · f(-1) Hz(2)/Hz in the 10 Hz < f < 10(5) Hz range, which is in good agreement with the VCSEL’s measured fractional frequency instability (Allan deviation) of ≈ 1 × 10(-8) at 1 s, and also is consistent with the VCSEL’s typical optical linewidth of 20-25 MHz. The VCSEL bias current can be directly modulated at 4.596 GHz with a microwave power of -6 to +6 dBm to generate optical sidebands for CPT excitation. With such a VCSEL, a 1.04 kHz linewidth CPT clock resonance signal is detected in a microfabricated Cs cell filled with Ne buffer gas. These results are compatible with state-of-the-art CPT-based miniature atomic clocks exhibiting a short-term frequency instability of 2-3 × 10(-11) at τ = 1 s and few 10(-12) at τ = 10(4) s integration time..
authors.affiliation: Time and Frequency Laboratory, Physics Department, University of Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Gruet
authors.forename: A
authors.initials: A
authors.lastname: Al-Samaneh
authors.forename: E
authors.initials: E
authors.lastname: Kroemer
authors.forename: L
authors.initials: L
authors.lastname: Bimboes
authors.forename: D
authors.initials: D
authors.lastname: Miletic
authors.forename: C
authors.initials: C
authors.lastname: Affolderbach
authors.forename: D
authors.initials: D
authors.lastname: Wahl
authors.forename: R
authors.initials: R
authors.lastname: Boudot
authors.forename: G
authors.initials: G
authors.lastname: Mileti
authors.forename: R
authors.initials: R
authors.lastname: Michalzik