Intensity Noise Transfer Through a Diode-Pumped Titanium Sapphire Laser System

Abstract

Abstract-In this paper, we investigate the noise performance and transfer in a titanium sapphire (Ti:S) laser system. This system consists of a DBR tapered diode laser, which is frequency doubled in two cascaded nonlinear crystals and used to pump the Ti:S laser oscillator. This investigation includes electrical noise characterizations of the utilized power supplies, the optical noise of the fundamental light, the second harmonic light, and finally the optical noise of the femtosecond pulses emitted by the Ti:S laser. Noise features originating from the electric power supply are evident throughout the whole transfer chain. It is demonstrated that improving the electrical noise provides an easy method for reducing the relative intensity noise (RIN) in all stages. The frequency doubled light is shown to have a higher RIN than the fundamental light. In particular, the cascaded system is seen to exhibit higher RIN than a setup with only a single nonlinear crystal. The Ti:S is shown to have a cut-off frequency around 500 kHz, which means that noise structures of the pump laser above this frequency are strongly suppressed. Finally, the majority of the Ti:S noise seems to originate from the laser itself, which partly can be explained by the effect of relaxation oscillation frequency.

Influence of pump beam shaping and noise on performance of a direct diode-pumped ultrafast Ti:sapphire laser

“…In a BA-DL operated far above threshold several spatial modes oscillate and competition between these modes may give rise to the observed increased intensity noise. The Ti:S shows a broad peak around 400 kHz, presumably originating from relaxation oscillation frequencies (ROF), matching well with the expectations for a pump power of 2.9 W according to the literature [29]. The ROF peak is followed by the cutoff frequency corresponding to the upper state lifetime (3.2 µs) of the Ti:S. The noise spectrum of Ti:S in the region above 2 MHz, was observed to be limited by the shot noise level, i.e.…”

“…This setup is similar to the one described in Ref. [29]. The power of the input laser beam was adjusted using a continuously variable neutral density (ND) filter, while the combination of a half-wave plate and a polarizing beam splitter (PBS) was used to control the power impinging on each photodiode of the balanced amplified photodetector (BAP) module (PDB450-AC, Thorlabs).…”

Directly diode-pumped, Kerr-lens mode-locked, few-cycle Cr:ZnSe oscillator

“…Instead, a more 'plateau'like noise structure is seen. Similar behaviour has also been observed for diode-pumped Ti:Sapphire oscillators, which has been attributed to the relaxation oscillations of the Ti:Sapphire laser itself [53,54]. To further investigate the transfer of pump noise, the pump source of the Cr:ZnSe oscillator was switched to a commercial fiber laser (Bktel Photonics, HPFL-370-1567).…”

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

“…This RIN of the laser diode will then be transferred through, and amplified by, the second harmonic process. This process and a description of how the RIN was measured has been published elsewhere 9 . Using a low noise power supply (Norlase Aurora One) for the laser system, the total RIN in the full measurement range was measured to be 0.064 % rms.…”