Optical back-action on the photothermal relaxation rate

Abstract

Photothermal effects can alter the response of an optical cavity, for example, by inducing self-locking behavior or unstable anomalies. The consequences of these effects are often regarded as parasitic and generally cause limited operational performance of the cavity. Despite their importance, however, photothermal parameters are usually hard to characterize precisely. In this work we use an optical cavity strongly coupled to photothermal effects to experimentally observe an optical back-action on the photothermal relaxation rate. This effect, reminiscent of the radiation-pressure-induced optical spring effect in cavity optomechanical systems, uses optical detuning as a fine control to change the photothermal relaxation process. The photothermal relaxation rate of the system can be accordingly modified by more than an order of magnitude. This approach offers an opportunity to obtain precise in-situ estimations of the parameters of the cavity, in a way that is compatible with a wide range of optical resonator platforms. Through this back-action effect we are able to determine the natural photothermal relaxation rate and the effective thermal conductivity of the cavity mirrors with unprecedented resolution.

Cancellation of photothermally induced instability in an optical resonator

“…(c-f by referring to their natural values obtained in the limit of no interaction between optical and mechanical modes (𝐺 = 0). The optical modification of these mechanical constants corresponds to a generalised optical spring effect [42], in affinity to the similar phenomenon in optomechanical systems where pure radiation pressure force modifies the mechanical susceptibility. Here, both radiation pressure and photothermal forces act together to modify the mechanical response.…”

Photothermal effect in macroscopic optomechanical systems with an intracavity nonlinear optical crystal

“…Analogous to the well-known phenomena of electromagnetically induced transparency [40,41] and optomechanically induced transparency [42][43][44], a cavity is realized with an extremely narrow linewidth through the coupling of the optical cavity and an intracavity object. The same research group that developed photothermally induced transparency has also demonstrated that the photothermal effect changes the optical response of the cavity [45].…”

Floquet control of optomechanical bistability in multimode systems

“…with θ(t) = Ω mod t + θ 0 . This indicates that an increasing modulation depth d involves increasingly many driving tones beyond the usual first order expansion [37][38][39][40][41][42].…”

“…These temporal control schemes also allow to overcome mode-competition inhibiting multiple mechanical modes to simultaneously experience amplification resulting in modelocked lasing of degenerate modes [36]. Additionally, recent studies investigated the characterization of the cavity's thermal properties based on Floquet techniques and measurement effects on the quantum mechanical properties in the mechanical ground state [37][38][39][40][41]. In this letter, we show that the Floquet driving approach offers dynamical control of the optomechanical bistability in multimode settings which presents a useful tool in the manipulation of optomechanical systems.…”

“…In addition to the dispersive optomechanical coupling, the cavity in experimental setups absorbs photons and heats up which in turn changes its refractive index and geometry. We acknowledge and model the heating process by the dynamics of the temperature deviation δ Ṫ(t) = g abs |α| 2 (t) − γ th δT(t)/2 and the resulting shift of the optical cavity frequency ω op ≈ ω op ( T) + ∂ω op ∂T (T(t) − T) = ω 0 + g T δT(t), due to this photo-thermo-refractive-shift mechanism (PTRS) [37][38][39][40][41][42]. Here, g abs denotes the temperature change due to linear photon absorption, γ th the thermalization rate, and g T parametrizes the linear thermal shift of the optical frequency.…”