Research On The Whispering-Gallery-Mode Microlasers

The microlaser based on whispering gallery mode resonator has the virtues of low threshold,high conversion efficiency,high speed modulation and so on,which also has a wide application prospect in optical integration,optical interconnection,optical neural network and optical communication.In this paper,the characteristics of microlasers based on whispering gallery mode are studied.A microsphere resonator and two microlasers with different structures are proposed.The main contents include:1.A WGM microlaser based on micro/nano fiber and dual erbium-doped microspheres is proposed.Erbium-doped microspheres were fabricated by doping of erbium ions directly by using the electrode discharge of a fusion splicer to melt the tapered fiber tip.The incident light diverges from the micro-nano fiber to the microsphere,which excites WGM resonance.The WGM light field interacts with erbium ions,which is an internal gain material,and results in the laser operation.The quality factor(Q)value of the equipment is as high as 1.4×10~4,with a threshold of0.33 m W.When the pump power continues to change from 4.6 m W to 7.5 m W,the laser wavelength moves from 1560.14 nm to 1560.49 nm,and the laser power can be tuned from 0.25μW to 0.41μW.2.A WGM resonator with L-shaped microcavity is proposed.The L-shaped microcavity was fabricated by femtosecond laser,fusion discharge and chemical etching.The quality factor is improved by placing two microspheres in the microcavity,one of which acts as a WGM resonator and the other acts as a change of light path to change the coupling position.The sensitivity and linearity of the device are-0.23 d B/%RH and 99.1%at room temperature of 25°C and relative humidity of30%-70%.The response time is as short as 240 ms during humidification and the recovery time is 453 ms.3.A WGM microlaser based on an open microcavity and an erbium-doped microsphere is proposed.The erbium-doped microsphere was obtained by using electrode discharge melting the etched erbium-doped fiber tip.Femtosecond laser and fusion technology were used to fabricate the open microcavity.The light propagated in the fiber core was coupled to the erbium-doped microsphere through evanescent field when the microcavity at the position just contacting the fiber core.The Q value of the device is 6089 and the laser threshold is 0.033 m W.The laser wavelength shifts from 1564.59 nm to 1565.6 nm when the pump power changes continuously in the range of 0.39～0.72 m W.The sensitivity of the microlaser to temperature and refractive index(RI)is 33.3 PM/°C and 26 nm/RIU,respectively,and the detection limit of humidity sensitivity is 4.87×10~5RIU.The microsphere resonator and microcavity laser proposed in this paper have the advantages of high integration,compact size and good performance.