Optical biosensor and method of operating the same

1. An optical biosensor comprising:

a biosensing unit configured to receive first and second optical signals originating from a phase-modulated optical signal, to output a sensing signal via transmission of the first optical signal through a first optical path that includes a sensing resonator, and to output a reference signal via transmission of the second optical signal through a second optical path that includes a reference resonator;

a detection unit configured to receive the sensing signal and the reference signal, to detect a first phase element of the sensing signal and a second phase element of the reference signal through a signal demodulation operation, and to detect a phase difference between the sensing signal and the reference signal according to the first phase element and the second phase element;

a signal processing unit configured to calculate a concentration of a bio-material based on the phase difference; and

a quadrature signal generation unit configured to supply a quadrature signal to the detection unit, the quadrature signal having a phase which is in quadrature with respect to the sensing signal and the reference signal.

2. The optical biosensor of claim 1 , wherein the first optical signal and the second optical signal have a same phase.

3. The optical biosensor of claim 1 , wherein the sensing resonator is configured such that a resonant wavelength thereof changes when the bio-material is combined with the sensing resonator, and the phase difference has a value that corresponds to an amount of change of the resonant wavelength of the sensing resonator.

4. The optical biosensor of claim 1 , wherein the detection unit is configured to receive a first quadrature signal and a second quadrature signal from the quadrature signal generation unit, to detect the first phase element of the sensing signal via performance of a first operation on the sensing signal and the first quadrature signal, and to detect the second phase element of the reference signal via performance of a second operation on the reference signal and the second quadrature signal.

5. The optical biosensor of claim 4 , wherein the detection unit is configured such that the performance of the first operation includes a division of the first quadrature signal into the sensing signal and an execution of an arctangent operation on a result of the division.

6. The optical biosensor of claim 4 , wherein the detection unit is configured to receive a clock signal having a known frequency and to output a counting result of the clock signal, the counting result corresponding to the phase difference between the sensing signal and the reference signal.

7. The optical biosensor of claim 1 , further comprising:

a light source configured to generate an optical signal; and

an interferometer configured to receive the optical signal and modulate a phase of the optical signal to generate the phase-modulated optical signal.

8. The optical biosensor of claim 1 , further comprising:

a database unit configured to store information regarding the concentration of the bio-material in connection with the phase difference.

9. A method of operating an optical biosensor, the method comprising:

receiving first and second optical signals originating from a phase-modulated optical signal;

outputting a sensing signal by transmitting the first optical signal via a first optical path that includes a sensing resonator;

outputting a reference signal by transmitting the second optical signal via a second optical path that includes a reference resonator;

detecting a first phase element of the sensing signal and a second phase element of the reference signal through a signal demodulation operation;

detecting a phase difference between the sensing signal and the reference signal according to the first phase element and the second phase element;

calculating a concentration of a bio-material based on the phase difference; and

generating first and second quadrature signals having a phase which is in quadrature with respect to the sensing signal and the reference signal.

10. The method of claim 9 , wherein the receiving includes the first optical signal and the second optical signal having a same phase.

11. The method of claim 9 , wherein the outputting a sensing signal includes combining the bio-material with the sensing resonator, a resonant wavelength of the sensing resonator changing with the combining, the phase difference having a value that corresponds to an amount of change of the resonant wavelength of the sensing resonator.

12. The method of claim 9 ,

wherein the detecting a first phase element of the sensing signal and a second phase element of the reference signal includes performing a first operation on the sensing signal and the first quadrature signal to detect the first phase element of the sensing signal and performing a second operation on the reference signal and the second quadrature signal to detect the second phase element of the reference signal.

13. The method of claim 9 , further comprising:

generating an optical signal; and

modulating a phase of the optical signal with an interferometer to generate the phase-modulated optical signal.

14. The method of claim 9 , wherein the calculating includes accessing a storage unit in which the concentration of the bio-material is databased and stored in connection with the phase difference.

15. An optical biosensor comprising:

a biosensing unit including a first optical path and a second optical path, the first optical path including a sensing resonator configured to be exposed to a bio-material, the second optical path including a reference resonator configured to be isolated from the bio-material, the first optical path configured to receive a first phase-modulated optical signal and to output a sensing signal, the second optical path configured to receive a second phase-modulated optical signal and to output a reference signal;

a detection unit connected to the biosensing unit, the detection unit configured to demodulate the sensing signal and the reference signal to detect a phase difference therebetween, the detection unit including,

a quadrature signal generation unit,

a demodulation unit, and

a phase delay calculation unit; and

a signal processing unit connected to the detection unit, the signal processing unit configured to calculate a concentration of the bio-material based on the phase difference between the sensing signal and the reference signal.

16. The optical biosensor of claim 15 , wherein the first optical path includes a first optical waveguide and a second optical waveguide, the sensing resonator arranged between the first optical waveguide and the second optical waveguide.

17. The optical biosensor of claim 16 , wherein the sensing resonator is spaced apart from the first optical waveguide by a first gap and spaced apart from the second optical waveguide by a second gap.

18. The optical biosensor of claim 15 , further comprising:

a coupler connected to the biosensing unit, the coupler configured to divide a phase-modulated input optical signal into the first phase-modulated optical signal and the second phase-modulated optical signal for transmission to the biosensing unit.