ZnSe-based birefringent waveguide as Pockels retarder in the blue-green spectral range

Abstract

Electro-refractive modulation in the blue-green spectral range is demonstrated in strained, MBE-grown ZnSe waveguides with cladding layers of ZnMnSe on n-GaAs substrates. Utilizing the Pockels effect in Schottky-contacted structures with built-in birefringence, a contrast ratio better than 80:1 at 2.485 eV is achieved. The rise time of (4.7±0.5) ns is RC limited.

ZnSe-based electro-optic waveguide modulators for the blue-green spectral range

“…The electrically induced shift of the interference fringes is towards higher photon energies for reverse bias U < −10 V and towards lower photon energies for forward bias (figure 3). As shown previously, a device consisting of an unstrained ZnSe bulk crystal does not exhibit such electro-optical birefringence modulation [11]. Generally, compensation between the built-in ( n 0 ) and electrically induced ( n eo ) birefringence may occur, resulting in an unstructured device transmission.…”

“…In the present study, continuing and extending previous work [11], we are dealing with the design and fabrication as well as the demonstration of efficient ZnSe modulators for the green-blue spectral range. Molecular beam epitaxy (MBE) allows us to tailor the structures in the desired way and guarantees the required structural and optical quality.…”

“…On the other hand, using the same voltage around operation point B (at a minimum of the interference fringes) leads to light output with doubled frequency (insert B). Measurements of the electrical bandwidth [11] reveal a rise time of 4.7 ± 0.5 ns limited by the capacity of the Schottky-contact. For a down-scaled contacted area of 10 4 µm 2 , we estimate an RC time of about 10 ps.…”

“…With stripe electrodes, an electrically controllable waveguide structure is formed, operating as a modulator or spatial switch. In a phase retarder setup, the intrinsically birefringent planar waveguide exhibits a contrast ratio better than 80:1 at a photon energy of 2.48 eV [11].…”