Highly efficient single-pass frequency doubling of a continuous-wave distributed feedback laser diode using a PPLN waveguide crystal at 488 nm

Abstract

A continuous-wave distributed feedback diode laser emitting at 976 nm was frequency doubled by the use of a periodically poled lithium niobate waveguide crystal with a channel size of 3 microm x 5 microm and an interaction length of 10 mm. A laser to waveguide coupling efficiency of 75% could be achieved resulting in 304 mW of incident infrared light inside the waveguide. Blue laser light emission of 159 mW at 488 nm has been generated, which equals to a conversion efficiency of 52%. The resulting wall plug efficiency was 7.4%.

Frequency doubling of incoherent light from a superluminescent diode in a periodically poled lithium niobate waveguide crystal

“…5. The broad band ASE was converted to a narrow band spectrum with a width of 80 pm (FWHM), dominated by the acceptance bandwidth of the PPLN crystal, which was measured to be ≈140 pm in the infrared spectrum (see inset of blue light could be generated, giving a conversion efficiency of about η shg,df b ≈ 300 %/W in the same waveguide channel, which is in accordance to previous results at higher powers [29,30].…”

Blue‐green light generation using high brilliance edge emitting diode lasers

“…Poling periods as short as 1.4 μm for SHG at a wavelength of 340 nm have been shown with MgO doped LN [23]. Conversion efficiencies of up to 3.4 %/W cm [24] for bulk materials and 200 %/W cm 2 for waveguides have been reported [25]. Crystals with a length of up to 70 mm are available from 3" wafers.…”

“…Today, with frequency doubled edge emitting diode lasers SHG output powers of up to 1.5 W in the visible spectrum can be achieved [110]. Furthermore, conversion efficiencies of up to 40% in single pass [25] and 75% [111] in resonant SHG setups have been demonstrated.…”

“…Recently, more than 150 mW cw emission at 488 nm could be generated with an 1.5 mm long DFB ridge waveguide diode laser and a 10 mm long PPLN waveguide crystal [25]. The experimental setup is depicted in Fig.…”

Deep modulation of second-harmonic light by wavelength detuning of a laser diode

“…The modulation scheme has previously been used to obtain MHz modulation of blue light for optical storage [10] and green light for laser displays [11]. In both cases a DBR laser and nonlinear crystals with channel waveguides were used, since these enable very high conversion efficiency [12]. SHG systems using channel waveguides in nonlinear crystals cannot be scaled to the multiple watt-level powers needed for medical treatment [13].…”