Fiber laser sensor based on multimode interference (MMI) effect can achieve high sensitivity with lower temperaturestrain cross sensitivity by designing optimally the MMI structure. An erbium-doped fiber laser for temperature, stress and refractive sensing based on single mode fiber spliced a short section of no-core fiber was proposed in this paper. The optical field characteristics of this MMI structure have been analyzed, indicating the spectral filtering effect existed. An erbium-doped fiber laser with the MMI structure inserted as the sensor element, the enhanced sensing sensitivity is achieved on the sensing experiments of ambient temperature, mechanical stress and liquid refractive index. The sensitivity of this MMI-based fiber laser sensor is up to 13.24 pm/°C with the measured range from 30 °C to 220 °C, 1.29pm/με from 0 to 7776.05με, 180.21nm/RIU from 1.34 to 1.42, respectively.
High power fiber laser was demonstrated by using Yb-doped double-clad fiber based on laser cavity consisted of both fiber Bragg gratings spliced onto fiber ends, which pumped by a fiber-coupled multimode laser diode (FMLD) with 970nm central wavelength. In our experiment star-shape double clad Ytterbium-doped fiber was used, the MAX output
power and center wavelength is 6W cw and central wavelength of 1100nm respectively, FWHM is about 0.66nm, the slope efficiency is about 51%.
Multiple quantum wells (MQW) microdisk lasers are fabricated by using the methods of photolithography-etching techniques. By the CCD watching-control and micron-area detecting systems, The 5µm-diameter microdisk lasers was optically pumped by Ar+ pulse laser at room temperature, with the 1:50 pump duty cycle. We obtained the single-mode lasing at 1.543&#61549m wavelength, with threshold pump power about 200µw.
Here we report a simulation of bending loss of a photonic wire ring resonator. The ring resonator and waveguide core are composed of InGaAs/InGaAsP, which is isolated by an InP spacer. The waveguide core below the ring resonator could be used as a bus waveguide. The dependence of coupling coefficient on the thickness of InP spacer is calculated.
Silicon-based photonic wire waveguide was designed. The waveguide was consisted of a sandwiched structure with a nanocrystalline silicon film embedded between two low index silicon oxide films. The conformal transformation method was used in the simulation to obtain the basic coupling characteristics. The results showed that the coupling coefficient was strongly dependent on the gap spacing and the radius of the ring waveguide. A coupling efficiency of 10% could be obtained when the gap spacing was about 0.3 micrometers .
In this work InGaAs/InGaAsP/InP microcylinder lasers with diameter of 10 micrometers were fabricated by wet chemical etching. At liquid nitrogen temperature the lasers show lasing at 1.55 micrometers when electrically pumped with pulse width 300 ns and cycle of 200 microsecond(s) . The threshold current is about 3 mA.
The semiconductor microcylinder lasers with whispering-gallery modes are expected to be with execllent performances, such as low threshold current density and high efficiency. The spontaneous emission characteristics of microcylinder laser due to microcavity effect is strongly modified. Another excellence of whispering-gallery mode devices is that the probability of planar integration with waveguide devices and detectors. In this work InGaAs/InGaAsP microcylinder laser was fabricated by wet chemical etching. The diameter of the microcylinder is about 10micrometers or 5micrometers . With our improved processing the microcylinder was with smooth side wall, ensuring high Q-factor. The lasing at about 1.5micrometers was observed at low temperature.
The lasing modes and the spontaneous emission factors of microdisk lasers are analyzed simply, in this paper, InGaAs/InGaAsP multiple quantum wells (MQW) microdisk lasers are fabricated by using the methods of active ion etching and selective chemical etching. The diameter of the microdisk lasers was 3 micrometers . InGaAs/InGaAsP MQW microdisk lasers was optically pumped when cooled with liquid nitrogen. We obtained the single-mode lasing at 1.5 micrometers wavelength, with threshold pump power 18 (mu) w.