Table 1.

Comparison of different approaches to realize tunable and reconfigurable metadevices.

Tuning Approach	Materials	External knots	Operation spectrum	Functionalities	Modulation range/speed	Ref.
Carrier doping	Semiconductors	Electrical	THz to Visible	modulator	55%/2MHz	[58]
		Optical			90%/NA	[38]
	Graphene	Electrical	THz to NIR	polarizer/absorber	243°/NA	[26]
					100%/20GHz	[77]
	TCO	Electrical	NIR to Visible	phase modulator	30%/10MHz	[52]
Phase transition	Liquid Crystals	Electrical	GHz to Visible	modulator/beam deflector/color filter	70%/NA	[84]
		Thermal			12°/NA	[111]
		Optical			18%/NA	[123]
	VO2	Electrical	THz to visible	modulator	80%/1KHz	[104]
		Thermal		modulator	20%/NA	[42]
		Optical		modulator	38%/NA	[39]
	GST	Electrical	THz to Visible	color tuning	100%/NA	[107]
		Thermal		beam switching	NA	[106]
		Optical		modulator	400%/10MHz	[40]
	Superconductor	Thermal	GHz to THz	modulator	35%/NA	[44]
Mechanics	MEMS/NEMS	Electromechanical	GHz to Visible	modulator	31%/1KHz	[31]
					8%/ to MHz	[33]
	Elasticity	Mechanical	GHz to Visible	Color tuning/Tunable lens	27%/NA	[94]
					NA/NA	[53]
	Microfluidics	Microfluidics	GHz to Visible	polarization converter/color printing	NA/NA	[35]
					NA/62Hz	[98]
Capacitance	Varactor/PIN diode	Electrical	MHz-GHz	Tunable lens/reprogrammable hologram	NA/NA	[48]
					NA/100KHz	[49]