SBIR-STTR Award

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.

A new means for generation of arrayed, highly coherent, optical emitters is described. The new technology unifies basic advantages of cavityless silicon mixer engineering to provide emitter performance that cannot be matched by conventional technology. In contrast to standard devices, the new, all-silicon device allows for free frequency tuning of emitter modes, spectral purity in excess of 45dB, and per-frequency power that is not attainable by conventional frequency combs. More importantly, the new emitter allows for sub-10dB spectral equalization over the entire telecommunication band, without compromising mutual coherency of the individual modes. Unlike previously reported devices, the new technology relies only on commercial, all-silicon foundry technology. The new emitter allows for qualitatively new performance in low-SWaP LIDARS, EW, ELINT and LPI systems.