Local density of optical states calculated by the mode spectrum in stratified media

The local density of optical states(LDOS)is an important physical concept,which can characterize the spontaneous emission of microcavities.In order to calculate the LDOS,the relationship between the mode spectrum and the LDOS is established.Then,based on the transfer matrix method and the effective resonator model,the leaky loss of the leaky mode and the mode spectrum in the one-dimensional photonic bandgap crystal waveguide are calculated,results of which indicate that the mode spectrum can characterize the leaky loss of the leaky mode.At last,the density of optical states(DOS),and the LDOS in each layer are calculated.The partial DOS and the partial LDOS in the quantum well,related to the fundamental leaky mode,can be used to find out the optimal location of the quantum well in the defect layer to couple more useful photons into the lasing mode for lasers.

Polarization full feedback external cavity of open loop spectral beam combining based on multi-single emitters laser diode

In this paper,a spectral beam combining(SBC)structure of multi-single emitters laser diode based on a polarization full feedback(PFF)external cavity is proposed and demonstrated.The maximum combining efficiency is 75.6%,which leads to an output power of 38.48 W,a degree of polarization(DOP)of 99.42%,and electro-optical conversion efficiency of 35.63%under continuous wave operation at a current of 8 A.Compared to the conventional SBC,the output power,the combining efficiency,the electro-optical conversion efficiency,and the DOP of the PFF-SBC structure present improvements of 5.73 W,11.26 percentage points,5.3 percentage points,and 7.26 percentage points,respectively.The results show that this SBC method can achieve a high efficiency and linearly polarized laser output of SBC,thereby making the subsequent polarization beam-combining efficiency approach the limit.

Detector-integrated vertical-cavity surfaceemitting laser with a movable high-contrast grating mirror

In this paper, we present a detector-integrated vertical-cavity surface-emitting laser(VCSEL) with a movable high-contrast grating(HCG) mirror in an n-i-p-i-n manner. The detector-integrated VCSEL with a movable HCG can achieve three functions, including wavelength tuning, power monitoring, and resonant-cavity-enhanced(RCE)photon detection. Currently, the device can achieve a wavelength tuning range of 27 nm at room temperature when the suspended HCG is driven by the reverse-bias voltage. The n-i-p structure located at the upper part of the device can serve as an intra-cavity photodiode to monitor the output power due to the defect absorption. The RCE photon detection function of the detector-integrated VCSEL with a movable HCG is measured, and it has a peak responsivity at about 926 nm. This detector-integrated VCSEL with a movable HCG will be useful for sensing and imaging.

Improving the performance of high-power broad-area lasers by suppressing cavity modes propagating in the lateral dimension

We first study the effect of cavity modes propagating in the lateral dimension on high-power semiconductor lasers with a large stripe width.A sidewall microstructure was fabricated to prevent optical feedback of lateral resonant modes.Theoretically,we demonstrate the existence of lateral resonant modes in the Fabry–Perot cavity with a large stripe width.Experimentally,we design the corresponding devices and compare them with conventional broad-area diode lasers.About a 15%reduction in threshold current and a 27%increase in maximum electro-optical conversion efficiency are achieved.The amplified spontaneous emission spectrum is narrowed,which proves that lateral microstructures suppress optical feedback of lateral resonant modes.Under a large continuous-wave operation,the maximum output power of laser device is43.03 W,about 1 W higher than that of the standard broad-area laser at 48 A.

Narrow vertical beam divergence angle for display applications of 645 nm lasers

We design a 645 nm laser diode(LD)with a narrow vertical beam divergence angle based on the mode expansion layer.The vertical beam divergence of 10.94°at full width at half-maximum is realized under 1.5 A continuous-wave operation,which is the smallest vertical beam divergence for such an LD based on the mode expansion layer,to the best of our knowledge.The threshold current and output power are 1.07 A and 0.94 W,limited by the thermal rollover for the 100μm wide and 1500μm long broad area laser,and the slope efficiency is 0.71 W/A.The low coherence device is fabricated with the speckle contrast of 3.6%and good directional emission.Such 645 nm LDs have promising applications in laser display.

High efficiency of spectral beam combining by using large optical cavity lasers

We studied the spectral beam combining[SBC]of a large optical cavity[LOC]laser array to achieve high-power and highbrightness laser output.We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses.We have found that using LOC laser diodes can increase the proportion of external cavity feedback,thereby improving the SBC efficiency.At a current of 90 A,the CW output power of the SBC system is 59.2 W,and the SBC efficiency reaches up to 102.8%.All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm,and the beam parameter product is 4.38 mm·mrad.

High peak power density and low mechanical stress photonic-band-crystal diode laser array based on non-soldered packaging technology

A high peak power density and low mechanical stress photonic-band-crystal(PBC)diode laser array based on non-soldered packaging technology is demonstrated.The array consists of the PBC diode laser bars with small fast axis divergence angles.Meanwhile,we design the non-soldered array structure that realizes mechanical stacking of 10 bars in the vertical direction.In the experiment,the peak power density of the PBC array is about 1.75 times that of the conventional array when the same total power is obtained.The peak power of the non-soldered array is 292.2 W,and the“smile”effect is improved by adjusting the mechanical fixing force of the array.