Integrated nonlinear photonics: emerging applications and ongoing challenges [Invited]

Abstract

We provide a review of recent progress in integrated nonlinear photonics with a focus on emerging applications in all-optical signal processing, ultra-low-power all-optical switching, and quantum information processing.

Photonic Quantum Noise Reduction with Low-Pump Parametric Amplifiers for Photonic Integrated Circuits

“…After defining α = A e −iφ , R 1 = (A 2 A 3 A 4 )/A 1 ; θ = φ 2 + φ 3 − φ 4 − φ 1 + (∆β + ∆β NL )dz, and κ = 2n γ (3) /k o1;4 (the overlap integral γ (3) , defined in Equation (B7) below), and substituting into Equation (7), we obtain the rate equations for the amplitude and the phase of the eigenvalue α 1 :…”

“…In the previous two sections, we have identified the parametric phase-dependent gain coefficient and the related parametric phase-pulling effect as fundamental mechanisms underpinning twophoton output per interaction for χ (2) and χ (3) parametric processes for any level of optical powers and conditions. In this section, we consider the possibility of generating sub-Poissonian distributions of photons with the assistance of optically linear parametric (OLP) [6] and electro-optic parametric (EOP) [7] interactions, which involve only one-photon output per interaction-with one-photon input-although the EOP conversion requires one microwave photon.…”

“…The reference phase φ pr is (the sum of) the pump phase(s). The gain coefficient is given by g o = γ (2m+1) ·P p m for a small signal and phase-matching conditions, with γ and P p corresponding, respectively, to the nonlinear coefficient and the pump power for χ (2) , the second-order susceptibility (m = 1 /2), and χ (3) , the third-order susceptibility (m = 1). The self-coupling term g o ·a s (0) of the rate equation (Equation (A2) above), would be generated by an electric dipole polarization oscillating at the angular frequency (2) ω pump + ω s instead of (2) ω pump − ω i , which is required for an exchange of photons of ω signal .…”

“…Integrated photonic platforms [1][2][3] will contain their own low-power optical sources, which will be used for on-chip signal processing. However, the low levels of power rule out any significant nonlinear effects for χ (2) and χ (3) , the second-and third-order susceptibilities.…”

“…Integrated photonic platforms [1][2][3] will contain their own low-power optical sources, which will be used for on-chip signal processing. However, the low levels of power rule out any significant nonlinear effects for χ (2) and χ (3) , the second-and third-order susceptibilities. For instance, a recently reported phase-sensitive amplifier [4] operating on χ (3) in semiconductor materials can only deliver output signal powers of less than −31 dBm for input pump powers of −1 dBm.…”