This disclosure relates to semiconductor quantum cascade lasers (QCLs). A three-terminal QCL device is disclosed. The three-terminal QCL device includes a unipolar multi-period quantum cascade laser structure embedded in a bipolar structure having three terminals providing at least two independently controllable biases to the QCL device for adjusting the lasing intensity and for tuning the lasing wavelength of the QCL device. The three-terminal QCL device further includes a quantum impedance matching structure for achieving high efficiency carrier injection and lowering lasing threshold. In addition, the multi-period quantum cascade laser structure is selectively doped to provide near charge neutrality during operation. The three-terminal QCL may further be controlled to achieve simultaneous dual- or multi-color lasing.

Provided is a tunable laser device. The tunable laser device includes a lower clad layer, first to third quantum well patterns disposed on the lower clad layer and arranged in a first direction parallel to a top surface of the lower clad layer, an upper clad layer disposed on the first quantum well pattern, and first grating patterns disposed between the third quantum well pattern and the lower clad layer. The first to third quantum well patterns are arranged in the first direction parallel to a top surface of the lower clad layer, the upper clad layer includes a p-type conductive clad layer, the upper clad layer includes an n-type conductive clad layer, and the third quantum well pattern is electrically intrinsic. When a reverse bias is applied to the upper clad layer, the third quantum well pattern, and the lower clad layer, the third quantum well pattern is changed in refractive index.

Provided is a multi-channel optical module device. The optical module device includes: a light source unit configured to include a plurality of laser diodes that are capable of wavelength modulation according to current; a beam splitter unit configured to include a plurality of beam splitters that have different reflectivity and transmissivity and reflect or transmit light output from each laser diode of the light source unit to output them in a first direction or a second direction; and an optical coupler configured to couple and output the light from the beam splitter unit. Center wavelengths of the laser diodes of the light source unit are different from each other, and the number of output channels varies according to the number of laser diodes.

Various technologies described herein pertain to injection locking on-chip laser(s) and external on-chip resonator(s). A system includes a first integrated circuit chip and a second integrated circuit chip. The first integrated circuit chip and the second integrated circuit chip are separate integrated circuit chips and can be optically coupled to each other. The first integrated circuit chip includes a laser configured to emit light via a first path and a second path. The second integrated circuit chip includes a resonator formed of an electrooptic material. The resonator can receive the light emitted by the laser of the first integrated circuit chip via the first path and return feedback light to the laser of the first integrated circuit chip via the first path. The feedback light can cause injection locking of the laser to the resonator to control the light emitted by the laser (e.g., via the first and second paths).

Provided is a multi-channel optical module device. The optical module device includes: a light source unit configured to include a plurality of laser diodes that are capable of wavelength modulation according to current; a beam splitter unit configured to include a plurality of beam splitters that have different reflectivity and transmissivity and reflect or transmit light output from each laser diode of the light source unit to output them in a first direction or a second direction; and an optical coupler configured to couple and output the light from the beam splitter unit. Center wavelengths of the laser diodes of the light source unit are different from each other, and the number of output channels varies according to the number of laser diodes.