2. Noise considerations in Ti:Sapphire pumping applications Self starting

3. What is Titanium Sapphire? Gain material widely used in commercially available femtosecond / tunable laser First laser based on Ti 3+ :Al 2 O 3 developed by Peter Moulton in 1982 (MIT Lincoln Laboratory) Operating wavelength range from 650- 1100nm, peak @ 800nm Broad gain bandwidth CW or mode-locked operation Shortest pulse: < 5fs (10 -15 s)

4. How the Ti:Sapphire laser works Broad excitation spectra 532nm DPSS lasers commonly used due to lifetimes and efficiency Emission spectra also broad: this is what makes Ti:Sapp so interesting Tuneable CW lasers Ultra short pulses

5. General Rule Noisy pump source gives noisy output –“Pump laser noise is found to transfer directly to the mode locked laser's amplitude” T.D. Mulder et al.,“Characterization of the Complex Noise Transfer Function of a Modelocked Ti:sapphire laser.” Lasers and Electro-Optics, 2007. CLEO 2007. –“The amplitude and envelope phase noise of mode locked laser are shown to depend directly on the pump laser amplitude stability” R.P Scott et al., “Amplitude and phase noise sensitivity of modelocked Ti:sapphire lasers in terms of a complex noise transfer function.” 2007/Vol 15 No 14/Optical Express

6. Frequency response to noise Like a swing, Ti:Sapp has a natural frequency response range Above a certain frequency pump noise is too fast for the lasing ions in Ti:sapphire to respond Below that frequency, noise is transferred through to output. For some applications, e.g. CEP, noise instability can prevent the application working

7. Noise Transfer Function Ryan P Scott et al. showed the response range of Ti:sapp falls off from 1MHz and has minimal transfer to laser noise above 10MHz This is the frequency range over which pump lasers must have low noise 2 R.P. Scott, T.D. Mulder, K.A. Baker, B.H. Kolner Opt. Express 15, 14, 2007