Time Delay Interferometry at UF

The main problem of any experimental verification of TDI is the time delay itself. Optical delay lines in the lab will never reach 16s time delays. Our group is developing a technique, which utilizes an electronic delay to generate a LISA-like signal within an optical set-up.

Laser 0 (the reference laser) transfers the frequency noise of Laser 1 into the RF or audio band

RF or audio signal will be digitized, delayed, and then regenerated at Laser 2.

Laser 0 transfers Laser 2 frequency noise into the RF or audio band

Demodulate S2 with time-delayed S1 Signal

The Demodulated signal can be used to phase lock the local laser, this is called transponder or arm locking.

The Demodulated signal can be used to form TDI-type linear combinations to cancel the laser frequency noise, as shown in the left-hand column.

LISA-like signals for Time Delay

The phase noise in this signal is a linear combination of the time-delayed phase noises of the far laser (Laser 1) and the reference laser (Laser 0) and of the actual phase noises of the local laser (Laser 2) and the reference laser. Important for us is the fact that the noise of our signal has the same characteristic of the noise of the LISA signal. Linear combinations similar to the ones derived for TDI cancel the laser frequency noise.
 

Our first experimental goal is a LISA-like interferometer with one laser representing each S/C. It can be used to verify TDI in all possible configurations. We will be able to also study timing problems and demonstrate arm locking.
 
 
RF-oscillators can be used to add USO noise; AOMs can be used to simulate Doppler shifts.

One additional laser per S/C can be added to generate a complete LISA-like interferometer.