Apparatus and method for detecting optical signal

An optical signal detecting apparatus comprising:

• a first optical coupling lens configured to transmit an incident light;
• an optical demultiplexer configured to demultiplex an optical signal transmitted from the first optical coupling lens;
• a second optical coupling lens configured to transmit the demultiplexed optical signal;
• and
• an optical detector configured to detect an optical signal transmitted from the second optical coupling lens,
• wherein the optical demultiplexer is connected to an input optical waveguide and an output optical waveguide.

An optical signal detecting method comprising:

• demultiplexing, by an optical demultiplexer, an input optical signal into a first optical signal having a first band wavelength and a second optical signal having a second band wavelength;
• detecting, by a first optical detector, an optical signal having a wavelength in a first band;
• and
• detecting, by a second optical detector, an optical signal having a wavelength not in the first band,
• wherein the optical demultiplexer, the first optical detector, and the second optical detector are provided in a TO-CAN package.