Mid-IR Multiwavelength Difference Frequency Generation Based on Fiber Lasers

A mid-IR multiwavelength difference frequency generation (DFG) laser source with fiber laser fundamental lights is demonstrated by using the dispersion property of PPLN to broaden the quasi-phase-matching (QPM) acceptance bandwidth (BW). Our results show that the QPM BW for the pump YDFL is much larger than that for the signal EDFL. Using a multiwavelength YDFL and a single-wavelength EDFL as the pump and the signal lights, the DFG laser source can simultaneously emit 14 mid-IR wavelengths with the spacing of 14nm at a fixed PPLN temperature. Moreover, mid-IR multiwavelength lasing lines can be synchronously tuned between 3.28 and 3.47μm

Consolidation effect of visual function training on children with different degrees of amblyopia

AIM: To observe the consolidation effect of visual function training in amblyopic therapy on children with amblyopia of different degrees(mild, moderate and severe)which had been normalized. <p>METHODS: Totally 78 amblyopic children were divided into two groups: visual function training group(<i>n</i>=36, 70 eyes)and control group(<i>n</i>=42, 67 eyes). The rollback situation of the two groups in 6, 12, 24 and 36 months were observed after visual acuity reached 0.9 during treatment.<p>RESULTS: The rollback rates were both 0 in visual function training group and control group with different degrees of amblyopia after 6 months. There was no significant difference in rollback rate between the 2 groups with different degrees of amblyopia after 6 and 12 months. There was no significant difference in rollback rate between the two groups with mild amblyopia after 24 and 36 months(<i>P</i>=0.269, 0.269). However, the rollback rate in training group with moderate amblyopia was significantly different from in control group after 24 and 36 months(<i>P</i>=0.004, 0.002). There was no significant difference in rollback rate between the two groups with severe amblyopia after 24 and 36 months. <p>CONCLUSION: Visual function training can reduce the rollback rate and consolidate the effect of amblyopic treatment effectively for children with moderate amblyopia. However, the effect is not as good for children with mild and severe amblyopia