. 2016 Apr 16;7(4):69. doi: 10.3390/mi7040069

Table 1.

Comparison of different configurations of MEMS/NEMS tunable Si photonic devices.

	Metrics	Principle	Applications	Remarks	Reference
Configurations		Principle	Applications	Remarks	Reference
Waveguide	Segmented	Transmission modulation	Switch	High extinction ratio	[30]
	Segmented	Transmission modulation	Motion detection	Moderate sensitivity	[35]
	Coupled	Evanescent coupling	Switch	High extinction ratio	[39,40,41,42]
			Phase modulator	High operation speed by deforming waveguides	[47]
			Wavelength tunable filter	Forming a ring resonator with adjustable round-trip length; low Q factor	[51]
	Evanescent field perturbation	Proximity perturbation	Phase modulator	High operation speed	[84]
			Switch	Moderate extinction ratio	[85]
			Switch, attenuator, or filter with non-monolithically integrated actuator	Complex fabrication process	[103,104]
Ring/Disk resonator	Add-drop filter with tunable gap between the resonator and channel waveguide	Coupling strength tuning; loss controlling	Switchable filter	Moderate extinction ratio	[53]
			Bandwidth tunable filter	Moderate bandwidth tuning range with slight resonance wavelength variation	[55,58,60,61]
			Switch	Moderate extinction ratio	[56]
	Add-drop filter with evanescent field perturbation	Proximity perturbation	Switchable filter	High extinction ratio	[80]
	Add-drop filter with evanescent field perturbation	Proximity perturbation	Wavelength tunable filter	Small tuning range	[81,105]
PhC cavity	Coupled	Mode splitting variation by tuning coupling strength	Resonance control for such as tunable filter or router	Wide tuning range of resonance wavelength, with drawbacks of split modes	[90,91,92,93]
	2D air-slot cavity	Cavity deformation	Dynamic optical signal processing	High operation speed	[97,98]
	Transversely split 1D cavity	Cavity deformation	Resonance control	Wide tuning range of resonance wavelength	[99]
	Longitudinally split 1D cavity	Cavity deformation	Q factor tuning	Wide Q factor tuning range with slight resonance wavelength variation	[100]
	Evanescent field perturbation	Proximity perturbation	Resonance control	Moderate tuning range of resonance wavelength, yet with energy loss induced by perturbation	[78,79,82,83]