Does anyone have experience with this system, and, if so, what is the minimum achievable linewidth?
Furthermore, do you know some problems that would lead to linewidth broadening and how to solve them?
I never used these laser diode but to answer this questions I would say that it depends on the stabilization scheme you want to go for.
The best linewidth after stabilization are obtained by using a Pound-Drever-Hall (PDH) lock technique. If you go for this you should get something good depending on your electronic feedback loop and your reference cavity which will serve as your frequency discriminator.
What are you looking for?
Nevertheless the usual problems with DL is the 1/f technical noise.
With this combination the minimum achievable line width is limited by the short term line width of the laser in the order of some 100kHz, depending on the laser diode (wavelength) you are actually using. The LIR110 Lock-In module offers only a modest bandwidth (max. about 10kHz), so it is only able to compensate drifts (with an appropriate reference), but cannot significantly reduce the linewidth. With a high bandwidth feedback loop, e.g. Pound-Drever-Hall locking to cavity, you can reduce the linewidth to typically some kHz.
These diode lasers are sensitive to mechanical or acoustic noise, a well isolated optical table and a quiet environment are helpful.
In my experience, the linewidth of DL100 after stabilization by using LIR 100 plus saturation absorption or polarization spectroscopy is about 300KHz-500KHz. You can check the linewidth by heterodyne detecting two DL 100 lasers to get the beating signal.
Numerous factors can broaden the linewidth. Besides mechanical vibration or acoustic noise, I believe that there are at least three probable reasons can induce the situation worse. 1) Misalignment of the grating in DL 100. You can check the threshold current of DL 100. If it is distinctly bigger than the default value, you need to adjust the grating. 2) Reflected laser into DL 100. It is likewise a common situation especially when you couple laser into a fiber. If this is the cause of linewidth broadening, you need to use a better optical isolator. 3) Electronic noise, which can couple into the laser or a frequency stabilization circuit from ground or space, especially when you use some kind of RF apparatus, for example, RF sources for AOMs or function generators. It is better to use a clean ground for the laser system.
Presently,I am using LIR110 to stabilise my homemade diode laser. It is stabilised by the Doppler free saturation resonance methods using Rb vapour cell. The long term frequency stability is around 100 kHz. I used LIR110 to stabilise DFB laser by the same method. I think, DL100+LIR110 can give the same 100 kHz long term frequency stability, or even better. I doubt that the DL100 linewidth can be improved using LIR110.
Thank you all for your answers.
Dr. Chapovsky, what do you modulate in order to get an error signal? I'm guessing you don't modulate the current?
I am using the LIR110 generator to modulate at small amplitude the laser diode current.
So I'm trying to get rid of RF noise coming from an AOM (or AOM driver).
Does anyone have any suggestions? Would ferrite beads help?