Narrow Linewidth Tunable Terahertz Radiation By Photomixing Without Servo-Locking

Dual-Frequency 780-nm Ti:Sa Laser for High Spectral Purity Tunable CW THz Generation

“…We have checked that the laser exhibits the same performances in terms of linewidth and frequency drift whatever its mean wavelength. Despite the relatively high pumping power, the presence of two active crystals in the laser and different filtering levels, these performances are similar to that usually obtained with a less complex two axis dual frequency laser at 1.55 µm [10]. These results are very encouraging since the inherently narrow beatnote that is achieved makes it possible to envisage down conversion and phase-locking to a microwave local oscillator provided that a voltage controlled tunability is implemented to the laser [17].…”

Bridging the gap between THz and microwave photonics through optoelectronic generation of interleaved combs Invited paper

“…The two Stokes waves are finally directed to the UTC-based antenna which emits the continuous THz radiation. In these conditions, the measured linewidth is found to be 500 Hz whatever the beating frequency, i.e., at least 40 times narrower than the width found previously without stimulated Brillouin narrowing [24]. This result leads to an enhancement of SNR as illustrated in Fig.…”

“…In this illustration the beatnote is set to 1.5 GHz and detected by a low-bandwidth photodiode. The phase noise of the optical carrier is measured using a self-heterodyne setup and by demodulating the signal in phase and quadrature (I&Q) [24]. Besides, the phase noise of the optical beatnote is directly measured at the output of a low-bandwidth photodiode using the same I&Q demodulation technique.…”

Investigation of the coupling between pump amplitude noise and differential phase noise in an Er,Yb:glass two-polarization dual-frequency solid-state laser

“…We have been involved during the last years in developing a photonic adjustable ultra-stable sub-millimeter and millimeter wave reference based on a dual frequency laser [9] locked to a single ultralow expansion cavity. In this framework the knowledge of the amplitude to phase coupling coefficient is essential in order to ensure the best possible stability of the beat note between the two optical laser lines [10][11][12][13]. Given the extremely low coupling coefficients we are expecting in this kind of solid-sate laser, a specific measurement setup has to be designed.…”