Erbium Doped Glass For Optical Amplification In Detecting A Photoplethysmography

A method of monitoring a physical parameter of a user, comprising:

• providing an amplification layer, the amplification layer configured to have a first excitation wavelength and generate a second excitation wavelength;
• generating by a light source light of a first wavelength, the first wavelength corresponding to the first excitation wavelength;
• receiving the light of a first wavelength at the amplification layer;
• generating light of a second wavelength at the amplification layer responsive to the received light of a first wavelength;
• transmitting the light of a second wavelength from the amplification layer to the user;
• receiving from the user and at a photodetector, the light of a second wavelength;
• and
• evaluating by a processor a health condition of a first user based on at least the light of a second wavelength received at the photodetector.

A device comprising:

• a housing, the housing comprising a back portion adapted to be placed adjacent to a user's skin, the back portion is at least partially comprised of a glass and the glass is doped with a rare earth metal;
• a first light source configured to generate light with a first wavelength and first intensity;
• an amplification layer further comprising a doped rare earth metal and with a first side and a second side, the amplification layer configured to receive light of the first wavelength and first intensity and transmit light of a second wavelength with a second intensity;
• a photodetector receiving light of the second wavelength from the user;
• and
• a processor configured to determine a physical condition of a user based on at least a signal received from the photodetector;
• wherein the first wavelength is an excitation frequency of the amplification layer and second intensity is higher than the first intensity.