Stable and low-spurious laser source for fast addressing multiple optical qubits spread over a 100 GHz bandwidth

Optical manipulation of photonic solid-state qubits such as rare-earth ions in single crystals need stable laser sources able to perform complex and high bandwidth excitation waveforms (adiabatic pulses, STIRAP, HSH pulses) [1,2]. Such waveforms can be generated using an acoustic-optical modulators (AOM) connected to an Arbitrary Waveform Generator (AWG) [4]. However, the limited bandwidth of AOMs sets a severe limitation in the bandwidth and frequency agility, typically a few MHz. Using an electro-optical modulator (EOM) such as a phase or an intensity modulator made of LiNbO3 make it possible to access to higher bandwidth, but it generates unwanted harmonics that can perturb the experiment, reducing the fidelity and/or the efficiency of the protocol [4]. There is currently no architecture able to give enough versatility and stability to perform parallel multiple qubit gates operations over a few GHz range.
Here we develop a laser source that is able to deliver high-bandwidth optical signals at multiple frequencies over a span of 10 GHz (scalable to 100 GHz), with low optical and RF phase and intensity noise. The central wavelengths can be tuned to match the resonance of the different species of optical qubit (in our case Eu3+, or Er3+ ions in solid-state matrices). The architecture is based on the combination of multiple fixed-frequency laser sources at 1.5 μm. Each laser is externally modulated with a LiNbO3 IQ optical modulator and goes through a narrow optical filters to obtain the required performances in terms of arbitrary pulse shaping, signal-to-noise ratio and spurious suppression. After the optical signal combination, a non-linear up-conversion can be performed with high efficiency in order to get, for example, a central emission at 580 nm, typical for Eu3+ resonance wavelength.
In this poster, we show the preliminary results in term of modulation bandwidth, spurious suppression and wavelength tuning.
[1] M. Tian, et Al., APPLIED OPTICS, 50, 36 (2011)
[2] A. Kinos, et Al., ArXiv 2103.15743 (2021)
[3] J. Etesse et Al., PRA, 103, 2 (2021)
[4] A. Walther, et Al., PRA? A 92, 022319 (2015)