Table 1 Summary of representative RI-based infrared guided-wave nanophotonic biochemical sensors

MZI

TM mode

SOI

2

~ 460 × 2π rad

N/A

N/A

~ 6 pg/mm²

[29]

MZI

Slot, Vernier effect

SNOI

7

1730 × 2π rad

1.29 × 10⁻⁵

60 nm/(ng/mm²)

0.155 pg/mm²

[80]

MZI embedded with PhC nanobeam

Slow light effect

SOI

0.016

1344 rad

N/A

N/A

N/A

[107]

Cascaded MZI and MRR

Vernier effect

SOI

5.4

21,500 nm

N/A

0.5 nm/(ng/ml)

0.1 ng/ml

[119]

Microracetrack resonator

N/A

SOI

Radius 0.005

70 nm

1 × 10⁻⁵ (i)^b

10 ng/ml

N/A

[33]

MRR

Photodetector integration

SOI

Radius 0.1

~ 18.8 nm

3.5 × 10⁻⁵

N/A

N/A

[38]

MRR array

TM mode, temperature compensation

SOI

N/A

135 nm

7 × 10⁻⁷

N/A

0.3 pg/mm²

[68]

MRR

90 nm thick

SOI

N/A

133 nm

~5 × 10⁻⁴ (i)

N/A

N/A

[71]

Microracetrack resonator

TM mode, 150 nm thick

SOI

5.053

270 nm

1.2 × 10⁻³ (i)

N/A

N/A

[72]

MRR

Suspended

SOI

Radius 0.005

310 nm

N/A

N/A

N/A

[74]

MRR array

Slot, 1310 nm wavelength^a

SNOI

Radius 0.07

246 nm

5 × 10⁻⁶

1.3 nm/(ng/mm²)

0.9 pg/mm²

[77]

MRR

SWG

SOI

Radius 0.01

440.5 nm

~ 3.9 × 10⁻⁴ (i)

~ 1 nm/nm

N/A

[90]

MRR

Multibox

SOI

Radius 0.03

579.5 nm

1.02 × 10⁻³ (i)

1900 pm/nm

0.313 nm (i)

[92]

Two cascaded MRR

Vernier effect

SOI

2.514

2169 nm

8.3 × 10⁻⁶

N/A

N/A

[114]

Two cascaded MRR

Vernier effect, suspended

SOI

Radius 0.05

4.6 × 10⁵ nm

4.8 × 10⁻⁶ (i)

N/A

N/A

[115]

Two cascaded double-MRR

Vernier effect, TM mode

SOI

~ 0.8

24,300 nm

N/A

N/A

N/A

[117]

Three cascaded MRR

Vernier effect

SOI

Radii 0.132 and 0.138

5866 nm

1.3 × 10⁻⁵ (i)

N/A

N/A

[118]

Microdisk resonator

TM mode

SOI

Radius 0.01

142 nm

6.8 × 10⁻⁴

TM 3 times of TE

N/A

[70]

Microdisk resonator

TM mode, suspended

SOI

Radius 0.0008

130 nm

8 × 10⁻⁴ (i)

N/A

N/A

[73]

Microdisk resonator

Horizontal slot

SiN_x/SiO₂/SiN_x on Si

Radius 0.0075

N/A

N/A

2.5 nm/(µg/ml)

30 ng/ml

[87]

PhC nanobeam cavity array

N/A

SOI

N/A

N/A

N/A

0.35 nm/nm

63 ag (i)

[45]

PhC H0 cavity

N/A

SOI

N/A

176 nm

N/A

N/A

20 pM

[50]

PhC WMC cavity coupled W1 waveguide

Suspended

SOI

N/A

103 nm

2.4 × 10⁻³ (i)

24.7 ± 4.5 nm/pg

490 ± 70 pg/mm² (i)

[52]

PhC L9 cavity

Slot, suspended

SOI

N/A

421 nm

1 × 10⁻⁵

N/A

N/A

[85]

PhC L55 cavity coupled W1 waveguide

Slow light effect

SOI

0.023

N/A

N/A

N/A

50 fM (3.35 pg/ml)

[102]

PhC L13 cavity coupled W1 waveguide

Slow light effect, defect holes

SOI

N/A

112 nm

1 × 10⁻⁷ (i)

N/A

1 fM (67 fg/ml)

[105]

PhC hetero cavity

Slot, suspended

SOI

N/A

1538 nm

7.8 × 10⁻⁶ (i)

N/A

N/A

[83]

PhC W1 waveguide

Slow light effect

SOI

0.02

174.8 nm

1.55 × 10⁻⁴

0.706 nm/(ng/mm²)

2.1 pg/mm²

[106]

Bragg grating

Slow light effect

SOI

0.038

150 nm

1 × 10⁻⁵

N/A

N/A

[58]

Phase-shifted Bragg grating

TM mode, 1310 nm wavelength

SOI

N/A

106 nm

1.62 × 10⁻⁴ (i)

N/A

N/A

[40]

Phase-shifted Bragg grating

Slot

SOI

0.132

340 nm

3 × 10⁻⁴ (i)

N/A

N/A

[86]