Disclosed is a current-injection organic semiconductor laser diode comprising a pair of electrodes, an optical resonator structure, and one or more organic layers including a light amplification layer composed of an organic semiconductor, which has a sufficient overlap between the distribution of excitor density and the electric field intensity distribution of the resonant optical mode during current injection to emit laser light.

A quantum cascade laser includes a semiconductor substrate, an optical waveguide formed on a first surface of the semiconductor substrate, and a temperature adjusting member. The optical waveguide includes a first region and a second region located on one side with respect to the first region in the optical waveguide direction of the optical waveguide. The first region generates a first light having a first wavelength, and the second region generates a second light having a second wavelength. The optical waveguide generates an output light having a frequency corresponding to a difference between the first wavelength and the second wavelength by difference-frequency generation. A recess for suppressing heat transfer between the first region and the second region is formed at a second surface of the semiconductor substrate. The temperature adjusting member includes a first temperature adjusting member for adjusting the temperature of the second region.

A distributed reflector (DR) laser may include a distributed feedback (DFB) region and a distributed Bragg reflector (DBR). The DFB region may have a length in a range from 30 micrometers (μm) to 100 μm and may include a DFB grating with a first kappa in a range from 100 cm.sup.−1 to 150 cm.sup.−1. The DBR region may be coupled end to end with the DFB region and may have a length in a range from 30-300 μm. The DBR region may include a DBR grating with a second kappa in a range from 150 cm.sup.−1 to 200 cm.sup.−1. The DR laser may additionally include a lasing mode and a p-p resonance frequency. The lasing mode may be at a long wavelength side of a peak of a DBR reflection profile of the DBR region. The p-p resonance frequency may be less than or equal to 70 GHz.

A high-power semiconductor chip and a preparation method therefor. The semiconductor chip comprises: a substrate (1), a lower confinement layer (2), a lower waveguide layer (3), an active layer (4), an upper waveguide layer (5), a lateral grating layer (10), an upper confinement layer (6), a contact layer (7), a current isolation dielectric layer (8) and a metal layer (9), sequentially arranged from bottom to top, wherein the lateral grating layer (10) comprises a plurality of groups of lateral gratings; the plurality of groups of lateral gratings are sequentially arranged in a first direction; the periods of the plurality of groups of lateral gratings are different from each other; each group of lateral gratings comprises a plurality of gratings; the plurality of gratings are arranged in a second direction; and the first direction intersects with the second direction. Providing a lateral grating layer (10) in a waveguide improves the propagation loss of the high-order lateral light mode in the waveguide, and achieves the aim of suppressing the lasing of the high-order lateral light mode; and providing a plurality of groups of gratings with different periods suppresses the lasing of an intensity oscillation light mode caused by single grating gain modulation and refractive index modulation, achieves the effect of suppressing lateral light intensity periodic oscillation and eliminates the formation of far-field double humps.

A two-dimensional photonic-crystal surface-emitting laser includes an active layer; and a photonic-crystal layer including a two-dimensional photonic-crystal light-amplification portion that is a first two-dimensional photonic-crystal region provided in a plate-shaped base body disposed on one side of the active layer, and includes an amplification-portion photonic band gap which is a photonic band gap formed between two photonic bands having a band edge at a predetermined point in a reciprocal lattice space, and a two-dimensional photonic-crystal light-reflection portion that is a second two-dimensional photonic-crystal region provided around the two-dimensional photonic-crystal light-amplification portion, and includes a reflection-portion photonic band gap which is a photonic band gap formed between two photonic bands having a band edge at the predetermined point of the reciprocal lattice space, wherein energy ranges of the amplification-portion photonic band gap and the reflection-portion photonic band gap partially overlap and are different.

Disclosed is a current-injection organic semiconductor laser diode comprising a pair of electrodes, an optical resonator structure, and one or more organic layers including a light amplification layer composed of an organic semiconductor, which has a sufficient overlap between the distribution of exciton density and the electric field intensity distribution of the resonant optical mode during current injection to emit laser light.

The grating layer of a surface emitting laser is divided into a first grating region and a second grating region along a horizontal direction. The second grating region is located at a middle area of the grating layer, while the first grating region is located in an outer peripheral area of the grating layer. Each of the first and second grating regions comprises a plurality of micro-grating structures. The grating period of the micro-grating structures in the first grating region is in accordance with the following mathematical formula: $.Math.=m\frac{\lambda }{2*n_{\mathrm{eff}}};$
in addition, the grating period of the micro-grating structures in the second grating region is in accordance with the following mathematical formula: $.Math.=o\frac{\lambda }{2*n_{\mathrm{eff}}}.$
Wherein, Λ is the length of grating period, λ is the wavelength of the laser light, n.sub.eff is the equivalent refractive index of semiconductor waveguide, m=1, and o=2. The first grating region is a first-order grating region, and the second grating region is a second-order grating region, so as to form a hybrid grating structure in the grating layer. The surface emitting laser emits laser light perpendicularly from a light-emitting surface defined by the second grating region.

A compound represented by the following formula (1) is an excellent near-infrared emitter. R.sup.1 to R.sup.6 are H or a substituent and R.sup.7 is represented by the following formula (2). Ar.sup.11 is an aryl group, R.sup.11 is a substituent other than an aryl group and n11 is 1 or more. ##STR00001##

The grating layer of a surface emitting laser is divided into a first grating region and a second grating region along a horizontal direction. The second grating region is located at a middle area of the grating layer, while the first grating region is located in an outer peripheral area of the grating layer. Each of the first and second grating regions comprises a plurality of micro-grating structures. The grating period of the micro-grating structures in the first grating region is in accordance with the following mathematical formula:

[00001]$\text{Λ}=\text{m}\frac{\text{λ}}{2\ast {\text{n}}_{eff}};$

in addition, the grating period of the micro-grating structures in the second grating region is in accordance with the following mathematical formula:

[00002]$\text{Λ}=\text{O}\frac{\text{λ}}{2\ast {\text{n}}_{eff}}.$

Wherein, Λ is the length of grating period, λ is the wavelength of the laser light, n.sub.eff is the equivalent refractive index of semiconductor waveguide, m=1, and o=2. The first grating region is a first-order grating region, and the second grating region is a second-order grating region, so as to form a hybrid grating structure in the grating layer. The surface emitting laser emits laser light perpendicularly from a light-emitting surface defined by the second grating region.

Disclosed are a current excitation type organic semiconductor laser containing a pair of electrodes, an organic laser active layer and an optical resonator structure between the pair of electrodes and a laser having an organic layer on a distributed feedback grating structure. The lasers include a continuous-wave laser, a quasi-continuous-wave laser and an electrically driven semiconductor laser diode.