Synthesis of a 30-Hz Linewidth Wave Tunable Over 500 GHz Hallal, Ayman; Bouhier, Steve; Bondu, Francois
IEEE transactions on microwave theory and techniques,
2017-April, 2017-4-00, 20170401, 2017-04, Volume:
65, Issue:
4
Journal Article
Peer reviewed
We report on a compact source of 30-Hz linewidth, low-phase noise electrical waves with 500-GHz tunability. These waves are generated by photomixing two distributed feedback laser diodes at 1550 nm, ...which are frequency stabilized on a fibered cavity. We demonstrate a phase noise suppression down to -90 dBc/Hz at 100-kHz carrier offset frequency of the beat note at 2-, 10-, 18-, 40-, and 92-GHz frequencies. The setup also displays a ~170-kHz frequency drift of the beat note at 10 GHz in the long term over a continuous 7.5-h locking period.
We report on an all-electrical locking of the optical frequency of a distributed feedback laser diode at 1548 nm tunable over 9 nm on a fibered Fabry-Perot cavity. We demonstrate a 7-MHz servo ...bandwidth and a frequency noise suppression down to 10 Hz/√Hz at 200-kHz carrier offset frequency in the error signal. From this signal, we estimate the laser linewidth to be 100 Hz at a 10-ms integration time. This stabilized laser will be a component of a compact source of continuous millimeter or submillimeter low phase noise electrical waves.
A dual-frequency 1.55 µm laser for CW low noise microwave, millimeter and sub millimeter wave synthesis is demonstrated, where frequency stabilization is possible on each wavelength independently. ...The solid state Er:Yb laser output power is 7 mW. The amplitude noise is -150 dBc/Hz at 1 MHz offset frequency. In free running regime, the frequency noise is 3.10(5)/f Hz/sqrt(Hz) (800 Hz on a 1µs timescale), better than commercial fibered or semi-conductor sources at this wavelength.
An optically carried microwave synthesis working at 40 GHz is demonstrated by using a two-frequency solid-state microchip laser inserted as a voltage-controlled oscillator inside a digital ...phase-locked loop. We report an in-loop relative frequency stability better than 2.5 × 10 -11 . The capabilities of the synthesis are illustrated with different frequency sweeping formats.
A beatnote, tunable from dc to 1 THz, provided by a dual-frequency laser is used to feed an unitravelling carrier photodiode in order to produce a highly coherent THz signal radiated by a ...transverse-electromagnetic-horn antenna. The THz signal is detected and analyzed by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature without phase locking the beatnote. So far, the dynamic range evolves from 58 dB at 282 GHz to 15 dB at 1.026 THz, and the measured linewidth is better than 30 kHz. Linewidth narrowing using a Brillouin fiber laser pumped by the dual-frequency laser leads to a beatnote of 500-Hz linewidth at 1 THz.
We present a direct and very fast calculation of the low frequency tail of the spectral density of thermal noise due to the thermal motion of matter in the cylindrical mirrors generally used in ...gravitational wave interferometric detectors. This calculation is based on the method recently proposed by Levin, that we extend to the case of finite mirrors, allowing one to study the aspect ratio dependence of the noise. Results are found in good agreement with those found in heavier preceding approaches, and provide a useful cross-check.
A fully fibered microwave-optical source at 1.5 µm is studied experimentally. It is shown that the beat note between two orthogonally polarized modes of a distributed-feedback fiber laser can be ...efficiently stabilized using an optical phase-locked loop. The pump-power-induced birefringence serves as the actuator. Beat notes at 1 GHz and 10 GHz are successfully stabilized to a reference synthesizer, passing from the 3 kHz free-running linewidth to a stabilized sub-Hz linewidth, with a phase noise as low as -75 dBc/Hz at 100 Hz offset from the carrier. Such dual-frequency stabilized lasers could provide compact integrated components for RF and microwave photonics applications.
A narrow linewidth THz source is reported. A beatnote provided by a dual-frequency laser is sent into a unitravelling carrier photodiode, and radiated by a transverse-electromagnetic-horn antenna. ...The emitted THz signal is detected by a subharmonic mixer coupled to an electrical spectrum analyzer. The measured linewidth is better than 30 kHz and tunable from DC to 770 GHz with a minimum 30 dB dynamic range.
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