Laser device with optical isolator

A laser device having an optical isolator function, the laser device comprising:

• a laser diode chip (100) configured to emit laser light;
• a wavelength selective filter (400);
• a collimating lens (200) configured to be installed on an optical path between the laser diode chip (100) and the wavelength selective filter (400) to collimate the light emitted from the laser diode chip (100);
• a 45 degree partial reflection mirror (300) configured to be installed on an optical path between the collimating lens (200) and the wavelength selective filter (400) to convert a direction of laser light which is moved to be horizontal to a bottom of a package to be vertical to the bottom of the package;
• and
• an optical isolator configured to be disposed on an optical path between the collimating lens (200) and the 45 degree partial reflection mirror (300) to prevent laser light reflected from the wavelength selective filter (400) from being fed back to the laser diode chip (100);
• and
• a λ/4 waveplate (450) configured to be disposed between the 45 degree partial reflection mirror (300) and the wavelength selective filter (400) to convert direct light of linear polarization which is emitted directly from the laser diode chip (100) into light of circular polarization and, light of circular polarization which is reflected in the a wavelength selective filter (400) into reflected light of linear polarization,
• wherein the (a) direct light of linear polarization, which is directly emitted from the laser diode chip (100) and the reflected light of linear polarization which is reflected from the wavelength selective filter, passes through the λ/4 waveplate, and arrives at the 45 degree partial reflection mirror are both perpendicular to one another.