Coherent communications and general optical sensing rely on highly coherent, low-noise optical carriers, by which information carried in phase quadratures and spectroscopic signatures can be decoded with high confidence. While the need for low-noise carriers is currently fulfilled by discrete single-wavelength emitters, the scaling of discrete emitter arrays for supporting typical sensing and communications needs easily violates the SWaP envelope of mobile and airborne platforms, rendering deployment infeasible. Besides these scalability limits, disjoint optical construction of individual emitters renders the frequency and phase of optical carriers uncorrelated and wandering in time, thereby forbidding joint detection of channels in which the relative phase of all channels must be known. Contrary to discrete arrays, a chip-scale emitter array can be constructed with optical performance comparable to discrete counterparts. This monolithic approach will allow orders of magnitude reduction of size and power consumption, brought by shared packaging and environmental (temperature) control. Furthermore, phase-coherent emitter arrays can be built with strict phase correlation among channels, rendering joint channel detection possible. RAM Photonics proposes a new class of emitters with 80 carriers, at 300 microWatts each and OSNR of 45dB, spaced on 100GHz or denser ITU grid.
